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ANSYS CFD-Post Standalone: ReferenceGuide

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Table of Contents1. CFX Launcher ............................................................................................................................................. 1

The Launcher Interface ..................................................................................................................... 1Menu Bar ....................................................................................................................................... 1Tool Bar ........................................................................................................................................ 4Working Directory Selector ............................................................................................................... 4Output Window ............................................................................................................................... 4Customizing the Launcher ................................................................................................................. 4CCL Structure ................................................................................................................................. 4Example: Adding the Windows Calculator ............................................................................................ 7

2. CFX Command Language (CCL) .................................................................................................................... 9CFX Command Language (CCL) Syntax ............................................................................................. 9Basic Terminology ........................................................................................................................... 9Simple Syntax Details ..................................................................................................................... 10

3. CFX Expression Language (CEL) .................................................................................................................. 13CEL Fundamentals ......................................................................................................................... 13Values and Expressions ................................................................................................................... 13CFX Expression Language Statements ............................................................................................... 14CEL Operators, Constants, and Expressions ........................................................................................ 15CEL Operators .............................................................................................................................. 15Conditional if Statement .................................................................................................................. 16CEL Constants .............................................................................................................................. 17Using Expressions .......................................................................................................................... 17CEL Examples .............................................................................................................................. 18Example: Reynolds Number Dependent Viscosity ................................................................................ 18Example: Feedback to Control Inlet Temperature ................................................................................. 19Examples: Using Expressions in ANSYS CFD-Post .............................................................................. 20CEL Technical Details .................................................................................................................... 20

4. Functions in ANSYS CFX ............................................................................................................................ 21CEL Mathematical Functions ........................................................................................................... 21Quantitative CEL Functions in ANSYS CFX ....................................................................................... 23Functions Involving Coordinates ....................................................................................................... 25CEL Functions with Multiphase Flow ................................................................................................ 25Quantitative Function List ............................................................................................................... 26area ............................................................................................................................................. 30areaAve ........................................................................................................................................ 31areaInt ......................................................................................................................................... 31ave .............................................................................................................................................. 32count ........................................................................................................................................... 33countTrue ..................................................................................................................................... 33force ............................................................................................................................................ 34forceNorm .................................................................................................................................... 35inside ........................................................................................................................................... 35length .......................................................................................................................................... 36lengthAve ..................................................................................................................................... 36lengthInt ...................................................................................................................................... 37mass ............................................................................................................................................ 37massAve ....................................................................................................................................... 37massFlow ..................................................................................................................................... 37Mass Flow Sign Convention ............................................................................................................. 38Tools > Command Editor Example .................................................................................................... 38Tools > Function Calculator Example ................................................................................................ 38massFlowAve ................................................................................................................................ 38massFlowAveAbs .......................................................................................................................... 39Advanced ..................................................................................................................................... 39Technical Note .............................................................................................................................. 39

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Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

massFlowInt ................................................................................................................................. 40massInt ........................................................................................................................................ 41maxVal ........................................................................................................................................ 41minVal ......................................................................................................................................... 41probe ........................................................................................................................................... 42rmsAve ........................................................................................................................................ 42sum ............................................................................................................................................. 42torque .......................................................................................................................................... 43volume ......................................................................................................................................... 43volumeAve ................................................................................................................................... 43volumeInt ..................................................................................................................................... 44

5. Variables in ANSYS CFX ............................................................................................................................. 45Hybrid and Conservative Variable Values ............................................................................................ 45Solid-Fluid Interface Variable Values ................................................................................................. 46List of Field Variables ..................................................................................................................... 46Common Variables Relevant for Most CFD Calculations ....................................................................... 47Variables Relevant for Turbulent Flows .............................................................................................. 49Variables Relevant for Buoyant Flow ................................................................................................. 51Variables Relevant for Compressible Flow .......................................................................................... 51Variables Relevant for Particle Tracking ............................................................................................. 52Variables Relevant for Calculations with a Rotating Frame of Reference ................................................... 52Variables Relevant for Parallel Calculations ........................................................................................ 53Variables Relevant for Multicomponent Calculations ............................................................................ 53Variables Relevant for Multiphase Calculations .................................................................................... 53Variables Relevant for Radiation Calculations ...................................................................................... 54Variables for Total Enthalpies, Temperatures, and Pressures ................................................................... 55Variables and Predefined Expressions Available in CEL Expressions ....................................................... 55List of Particle Variables .................................................................................................................. 64Particle Track Variables ................................................................................................................... 64Particle Field Variables .................................................................................................................... 65Miscellaneous Variables .................................................................................................................. 70

6. ANSYS FLUENT Field Variables Listed by Category ........................................................................................ 79Alphabetical Listing of ANSYS FLUENT Field Variables and Their Definitions ........................................ 92Variables A-C ................................................................................................................................ 92Variables D-J ................................................................................................................................ 97Variables J-R ............................................................................................................................... 104Variables R ................................................................................................................................. 110Variables S .................................................................................................................................. 114Variables T-Z ............................................................................................................................... 119

7. Command Actions ..................................................................................................................................... 129Overview of Command Actions ...................................................................................................... 129File Operations from the Command Editor Dialog Box ........................................................................ 130Loading a Results File ................................................................................................................... 130Reading Session Files ................................................................................................................... 130Saving State Files ......................................................................................................................... 131Reading State Files ....................................................................................................................... 132Creating a Hardcopy ..................................................................................................................... 134Importing External File Formats ...................................................................................................... 134Exporting Data ............................................................................................................................ 134Viewer Controls ........................................................................................................................... 135Quantitative Calculations in the Command Editor Dialog Box .............................................................. 136Other Commands ......................................................................................................................... 136Deleting Objects .......................................................................................................................... 136Viewing a Chart ........................................................................................................................... 136Turbo Post CCL Command Actions ................................................................................................. 136

8. Power Syntax in ANSYS CFX ..................................................................................................................... 137Examples of Power Syntax ............................................................................................................. 137Example 1: Print the Value of the Pressure Drop Through a Pipe ........................................................... 138


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ANSYS CFD-Post Standalone: Reference Guide

Example 2: Using a for Loop .......................................................................................................... 138Example 3: Creating a Simple Subroutine ......................................................................................... 139Example 4: Creating a Complex Quantitative Subroutine ..................................................................... 139Predefined Power Syntax Subroutines .............................................................................................. 140Subroutine Descriptions ................................................................................................................. 141Usage ......................................................................................................................................... 141Power Syntax Subroutines .............................................................................................................. 141

9. Line Interface Mode .................................................................................................................................. 151Features Available in Line Interface Mode ......................................................................................... 151

Glossary ..................................................................................................................................................... 153Index ......................................................................................................................................................... 167

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ANSYS CFD-Post Standalone: Reference Guide

List of Figures1.1. CFX Launcher .......................................................................................................................................... 13.1. Temperature feedback loop ........................................................................................................................ 194.1. Backflow ................................................................................................................................................ 405.1. r and theta with Respect to the Reference Coordinate Frame ............................................................................. 62

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List of Tables3.1. CEL operators ......................................................................................................................................... 163.2. CEL Constants ........................................................................................................................................ 174.1. Standard Mathematical CEL Functions ......................................................................................................... 224.2. Examples of the Calling Syntax for an Expression .......................................................................................... 254.3. CEL Multiphase Examples ......................................................................................................................... 264.4. CEL Functions in CFX-Pre/CFX-Solver and in CFD-Post ................................................................................ 275.1. Common CEL Single-Value Variables and Predefined Expressions .................................................................... 565.2. Common CEL Field Variables and Predefined Expressions ............................................................................... 576.1. Pressure and Density Categories ................................................................................................................. 806.2. Velocity Category ..................................................................................................................................... 816.3. Temperature, Radiation, and Solidification/Melting Categories ......................................................................... 826.4. Turbulence Category ................................................................................................................................. 836.5. Species, Reactions, Pdf, and Premixed Combustion Categories ......................................................................... 846.6. NOx, Soot, and Unsteady Statistics Categories ............................................................................................... 856.7. Phases, Discrete Phase Model, Granular Pressure, and Granular Temperature Categories ....................................... 866.8. Properties, Wall Fluxes, User Defined Scalars, and User Defined Memory Categories ........................................... 876.9. Cell Info, Grid, and Adaption Categories ...................................................................................................... 886.10. Grid Category (Turbomachinery-Specific Variables) and Adaption Category ...................................................... 896.11. Residuals Category ................................................................................................................................. 906.12. Derivatives Category ............................................................................................................................... 916.13. Acoustics Category ................................................................................................................................. 92

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Chapter 1. CFX LauncherThis chapter describes the CFX Launcher in detail:

• The Launcher Interface (p. 1)

• Customizing the Launcher (p. 4)

The Launcher InterfaceThe layout of the CFX Launcher is shown below:

Figure 1.1. CFX Launcher

The CFX Launcher consists of a menu bar, a tool bar for launching applications, a working directory selector, andan output window where messages are displayed. On Windows platforms, an icon to start Windows Explorer in theworking directory appears next to the directory selector.

Menu BarThe CFX Launcher menus provide the following capabilities:

File MenuSaves the contents of the text output window and to close the launcher.

Save AsSaves the contents of the output window to a file.

QuitShuts down the launcher. Any programs already launched will continue to run.

Edit MenuClears the text output window, finds text in the text output window and sets options for the launcher.

ClearClears the output window.

FindDisplays a dialog box where you can search the text in the output window.

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OptionsPresents the Options dialog box, which allows you to change the appearance of the launcher.

GUI Style

There are a number of GUI styles that you can chose from, and are available on all platforms. For example, choosingWindows will change the look and feel of the GUI to resemble that of a Windows application. You can select fromWindows, Motif, SGI, Platinum, and CDE (Solaris) styles. Once you have selected a style, click Apply to test.

Application Font and Text Window Font

The button to the right of Application Font sets the font used anywhere outside the text output window. The buttonto the right of Text Window Font applies only to the text output window. Clicking either of these buttons opensthe Select Font dialog box.

CFX MenuAllows you to run the different modules of the CFX and other CFX products, if they are installed.

CFX-PreRuns CFX-Pre, with the working directory as specified in Working Directory Selector (p. 4).

CFX-Solver ManagerRuns CFX-Solver Manager, with the working directory as specified in Working Directory Selector (p. 4).

CFD-PostRuns CFD-Post, in the current working directory as specified in Working Directory Selector (p. 4).

Other CFX ApplicationsThe launcher also searches for other CFX applications (for example, ANSYS TurboGrid) and provides a menuentry to launch the application. If an application is not found, you can add it; for details, see Customizing theLauncher (p. 4).

ANSYS MenuAny version of ANSYS and ANSYS Workbench that you have installed can be launched from this menu. If anapplication is not found, you can add it; for details, see Customizing the Launcher (p. 4).

Show MenuAllows you to show system, installation and other information.

Show InstallationDisplays information about the version of CFX that you are running.

Show AllDisplays all of the available information, including information about your system, installation and variables.

Show SystemDisplays information about the CFX installation and the system on which it is being run.

Show VariablesDisplays the values of all the environment variables that are used in CFX.

Show PatchesDisplays the output from the command cfx5info -patches. This provides information on patches that havebeen installed after the initial installation of CFX.


2 Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

Menu Bar

Show AcknowledgementsDisplays a list of software and trademark acknowledgements.

Show TermsDisplays the license terms under which CFX is provided.

Tools MenuAllows you to access license-management tools and a command line for running other CFX utilities.

ANSYS License ManagerIf ANSYS License Manager is installed, a menu entry to launch it appears in the Tools menu.

Command LineStarts a command window from which you can run any of the CFX commands via the command line interface. Thecommand line will be set up to run the correct version of CFX and the commands will be run in the current workingdirectory.

On Windows, if you do not use the Tools > Command Line command to open a command window, then you willhave to either type the full path of the executable in each command, or explicitly set your system path to includethe <CFXROOT>/bin directory.

You may want to start components of CFX from the command line rather than by clicking the appropriate buttonon the launcher for the following reasons:

• CFX contains some utilities (for example, a parameter editor) that can be run only from the command line.

• You may want to specify certain command line arguments when starting up a component so that it starts up ina particular configuration.

• If you are having problems with a component, you may be able to get a more detailed error message by startingthe component from the command line than you would get if you started the component from the launcher. Ifyou start a component from the command line, any error messages produced are written to the command linewindow.

Configure User Startup Files (UNIX only)Information about creating startup files can be found in the installation documentation.

Edit FileOpens a browser to edit the text file of your choice in a platform-native text editor. Which text editor is called iscontrolled by the settings in <CFXROOT>/etc/launcher/shared.ccl.

Edit Site-wide Configuration FileOpens the site-wide configuration file in a text editor. Which text editor is called is controlled by the settings in<CFXROOT>/etc/launcher/CFX5.ccl.

User MenuThe User menu is provided as an example. You can add your own applications to this menu, or create new menus;for details, see Customizing the Launcher (p. 4).

Help MenuThe Help menu enables you to view tutorials, user guides, and reference manuals online. For related information,see Accessing Online Help (p. 9).

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Menu Bar

Tool BarThe toolbar contains shortcuts to the main components of CFX, for example CFX-Pre, CFX-Solver Manager andCFD-Post. Pressing any of the buttons will start up the component in the specified working directory. The equivalentmenu entries for launching the components also show a keyboard shortcut that can be used to launch the component.

Working Directory SelectorWhile running CFX, all the files that are created will be stored in the working directory. If you run the software onUNIX, the working directory is the directory that was current when you started the software. If you run the softwareon Windows, the launcher shows the working directory.

To change the working directory, you can do any of the following:

• Type the directory name into the box and press Enter.

• Click on the down-arrow icon ( ) next to the directory name. This displays a list of recently used directories.

• Click Browse to browse to the directory that you want.

Output WindowThe output window is used to display information from commands in the Show menu. You can right-click in theoutput window to show a shortcut menu with the following options:

• Find: Displays a dialog box where you can enter text to search for in the output.

• Select All: Selects all the text.

• Copy Selection: Copies the selected text.

• Save As: Saves the output to a file.

• Clear: Clears the output window.

Customizing the LauncherMany parts of the launcher are driven by CCL commands contained in configuration files. Some parts of the launcherare not editable (such as the File, Edit and Help menus), but others parts allow you to edit existing actions andcreate new ones (for example, launching your own application from the User menu). The following sections outlinethe steps required to configure the launcher. The configuration files are located in the<CFXROOT>/etc/launcher/ directory (where <CFXROOT> is the path to your installation of CFX). Youcan open these files in any text editor, but you should not edit any of the configuration files provided by CFX, otherthan the User.ccl configuration file.

CCL StructureThe configuration files contain CCL objects that control the appearance and behavior of menus and buttons thatappear in the launcher. There are three types of CCL objects: GROUP, APPLICATION and DIVIDER objects. Thefact that there are multiple configuration files is not important; applications in one file can refer to groups in otherfiles.

An example of how to add a menu item for the Windows calculator to the launcher is given in Example: Addingthe Windows Calculator (p. 7).

GROUPGROUP objects represent menus and toolbar groups in the launcher. Each new GROUP creates a new menu andtoolbar. Nothing will appear in the menu or toolbar until you add APPLICATION or DIVIDER objects to the group.An example of a GROUP object is given below:

GROUP: CFX Position = 200 Menu Name = &CFX



Tool Bar

Show In Toolbar = Yes Show In Menu = Yes Enabled = YesEND

• The group name is set after the colon. In this case, it is “CFX”. This is the name that APPLICATION andDIVIDER objects will refer to when you want to add them to this group. This name should be different to allother GROUP objects.

• Position refers to the position of the menu relative to others. The value should be an integer between 1 and1000. Groups with a higher Position value, relative to other groups, will have their menu appear further tothe right in the menu bar. Referring to Figure 1.1, “CFX Launcher” (p. 1), CFX has a lower position valuethan the ANSYS group. The File and Edit menus are always the first two menus and the Help menu is alwaysthe last menu.

• The title of the menu is set under Menu Name (this menu has the title CFX). The optional ampersand is placedbefore the letter that you wish to act as a menu accelerator (for example, Alt+C displays the CFX menu). Youmust be careful not to use an existing menu accelerator.

• The creation of the menu or toolbar can be toggled by setting the Show in Menu and Show in Toolbaroptions to Yes or No respectively. For example, you may want to create a menu item but not an associatedtoolbar icon.

• Enabled sets whether the menu/toolbar is available for selection or is greyed out. Set the option to No to greyit out.

APPLICATIONAPPLICATION objects create entries in the menus and toolbars that will launch an application or run a process.Two examples are given below with an explanation for each parameter. The first example creates a menu entry inthe Tools menu that opens a command line window. The second example creates a menu entry and toolbar buttonto start CFX-Solver Manager.

APPLICATION: Command Line 1 Position = 300 Group = Tools Tool Tip = Start a window in which CFX commands can be run Menu Item Name = Command Line Command = <windir>\system32\cmd.exe Arguments = /c start Show In Toolbar = No Show In Menu = Yes Enabled = Yes OS List = winntENDAPPLICATION: CFXSM Position = 300 Group = CFX Tool Tip = Launches ANSYS CFX-Solver Manager Menu Item Name = CFX-&Solver Manager Command = cfx5solve Show In Toolbar = Yes Show In Menu = Yes Enabled = Yes Toolbar Name = ANSYS CFX-Solver Manager Icon = LaunchSolveIcon.xpm Shortcut = CTRL+SEND

• The application name is set after the colon, in the first example it is “Command Line 1”. This name shouldbe different to all other APPLICATION objects.

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CCL Structure

• Position: sets the relative position of the menu entry. The value should be an integer between 1 and 1000.The higher the value, relative to other applications that have the same group, the further down the menu or thefurther to the right in a toolbar the entry will appear. If you do not specify a position, the object assumes a highposition value (so it will appear at the bottom of a menu or at the right of a group of buttons).

• Group: sets the GROUP object to which this application belongs. The value must correspond to the name thatappears after “GROUP:” in an existing GROUP object. The menu and/or toolbar entry will not be created if youdo not specify a valid group name. The GROUP object does not have to be in the same configuration file.

• Tool Tip: displays a message when the mouse pointer is held over a toolbar button. In the ‘Command Line1' example above, the Tool Tip entry is not used since a toolbar button is not created. This parameter isoptional.

• Menu Item Name: sets the name of the entry that will appear in the menu. If you do not specify a name, thename is set to the name of the APPLICATION: object. The optional ampersand is placed before the letter thatyou want to have act as a menu accelerator (for example, alt+c then s will start CFX-Solver Manager. Alt+cselects the CFX menu and “s” selects the entry from the menu). You must be careful not to use an existing menuaccelerator.

• Command: contains the command to run the application. The path can be absolute (that is, use a forward slashto begin the path on UNIX, or a drive letter on Windows). If an absolute path is not specified, a relative pathfrom <CFXROOT>/bin/ is assumed. If no command is specified, the menu item/toolbar button will not appearin the CFX Launcher. The path and command are checked when the CFX Launcher is started. If the path orcommand does not exist, the menu item/toolbar button will not appear in the launcher. You may find it usefulto include environment variables in a command path; for details, see Including Environment Variables (p. 7).

• Arguments: specifies any arguments that need to be passed to the application. The arguments are appendedto the value you entered for Command. You do not need to include this parameter as there are no arguments topass. You may find it useful to include environment variables in the arguments; for details, see IncludingEnvironment Variables (p. 7).

Distinct arguments are space-separated. If you need to pass an argument that contains spaces (for example, aWindows file path) you should include that argument in double quotes, for example:

Arguments = “C:\Documents and Settings\User” arg2 arg3

• Show In Toolbar: determines if a toolbar button is created for the application. This optional parameter hasa default value of Yes.

• Show In Menu: determines if a menu entry is created for the application. This optional parameter has a defaultvalue of Yes.

• Enabled: allows you to grey out the menu entry and toolbar button. Set this parameter to No to grey out theapplication. This optional parameter has a default value of Yes.

• OS List is an optional parameter that allows you to set which operating system the application is suitable for.If OS List is not supplied, the launcher will attempt to create the menu item and toolbar button on all platforms.

For example, the command to open a command line window varies depending on the operating system. In the‘Command Line 1' example above, the application only applies to Windows platforms. To complete the OScoverage, the launcher configuration files contain more ‘Command Line' applications that apply to differentoperating systems.

OS List can contain the following values: winnt (Windows, including Windows XP), aix (IBM), hpux,(HP), hpux-ia64 (64-bit HP), solaris (Sun), linux, linux-ia64 (64-bit Linux).

• Toolbar Name: sets the name that appears on the toolbar button. This parameter is optional (since you mayonly want to show an icon).

• Icon: specifies the icon to use on the toolbar button and in the menu item. The path can be absolute (that is,use a forward slash to begin the path on UNIX, or a drive letter on Windows). If an absolute path is not specified,a relative path from <CFXROOT>/etc/icons is assumed. The following file formats are supported for iconimage files: Portable Network Graphics (png), Pixel Maps (ppm, xpm) and Bitmaps (bmp). Other icons usedin the launcher are 32 pixels wide and 30 pixels high. This parameter is optional. If it is not included, an iconwill not appear.

• Shortcut: specifies the keyboard shortcut that can be pressed to launch the application. You must be carefulnot to use a keyboard shortcut that is used by any other APPLICATION object.



CCL Structure

Including Environment VariablesIn can be useful to use environment variables in the values for some parameters. You can specify an environmentvariable value in any parameter by including its name between the < > symbols. In the ‘Command Line 1' exampleabove, <windir> is used in the Command parameter so that the command would work on different versions ofWindows. <windir> is replaced with the value held by the windir environment variable. The Command andArgument parameters are the only parameters that are likely to benefit from using environment variables.Environment variables included in the Arguments parameter are expanded before they are passed to the application.

DIVIDERDIVIDER objects create a divider in a menu and/or toolbar (see the Tools menu for an example). An example ofthe CCL for DIVIDER objects is shown below.

DIVIDER: Tools Divider 1 Position = 250 Group = Tools OS List = winnt, aix, hpux, hpux-ia64, linux, linux-ia64, solarisEND

The Position, Group and OS List parameters are the same as those used in APPLICATION objects. Fordetails, see APPLICATION (p. 5).

Example: Adding the Windows CalculatorThe following CCL is the minimum required to add the Windows calculator to the launcher:

GROUP: Windows Apps Menu Name = WindowsENDAPPLICATION: Calc Group = Windows Apps Command = <windir>\system32\calc.exe Toolbar Name = CalcEND

Although the parameter Toolbar Name is not strictly required, you would end up with a blank toolbar button if itwere not set.

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Example: Adding the Windows Calculator

Chapter 2. CFX Command Language (CCL)The CFX Command Language (CCL) is the internal communication and command language of ANSYS CFX. Itis a simple language that can be used to create objects or perform actions in the post-processor. All CCL statementscan be classified into one of three categories:

• Object and parameter definitions, which are described in Object Creation and Deletion (p. 257).

• CCL actions, which are commands that perform a specific task (such as reading a session file) and which aredescribed in Command Actions (p. 129).

• Power Syntax programming, which uses the Perl programming language to allow loops, logic, and custommacros (subroutines). Power Syntax enables you to embed Perl commands into CCL to achieve powerfulquantitative Post-processing. For details, see Power Syntax in ANSYS CFX (p. 137).

State files and session files contain object definitions in CCL. In addition, session files can also contain CCL actioncommands. You can view and modify the CCL in these files by using a text editor.

For more information, see Object Creation and Deletion (p. 257).

CFX Command Language (CCL) SyntaxThe following topics will be discussed:

• Basic Terminology (p. 9)

• Simple Syntax Details (p. 10)

• Case Sensitivity (p. 10)

• CCL Names Definition (p. 10)

• Indentation (p. 10)

• End of Line Comment Character (p. 10)

• Continuation Character (p. 11)

• Named Objects (p. 11)

• Singleton Objects (p. 11)

• Parameters (p. 11)

• Lists (p. 11)

• Parameter Values (p. 11)

• Escape Character (p. 12)

Basic TerminologyThe following is an example of a CCL object that defines an isosurface.

ISOSURFACE: Iso1 Variable = Pressure Value = 15000 [Pa] Color = 1,0,0 Transparency = 0.5END

• ISOSURFACE is an object type

• Iso1 is an object name

• Variable = Pressure is a parameter

• Variable is a parameter name

• Pressure is a parameter value

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• If the object type does not need a name, it is called a singleton object. Only one object of a given singleton typecan exist.

The Data HierarchyData is entered via parameters. These are grouped into objects that are stored in a tree structure.

OBJECT1: object name name1 = value name2 = valueEND

Objects and parameters may be placed in any order, provided that the information is set prior to being used furtherdown the file. If data is set in one place and modified in another, the latter definition overrides the first.

In CFD-Post, all object definitions are only one object level deep (that is, objects contain parameters, but not otherobjects).

Simple Syntax DetailsThe following applies to any line that is not a Power Syntax or action line (that is, the line does not start with a !or >).

Case SensitivityEverything in the file is sensitive to case.

Case sensitivity is not ideal for typing in many long parameter names, but it is essential for bringing the CFXExpression Language (CEL) into CCL. This is because some names used to define CCL objects (such as Fluids,Materials and Additional Variables) are used to construct corresponding CEL names.

For simplicity and consistency, the following is implemented:

• Singletons and object types use upper case only.

• Parameter names, and predefined object names, are mixed case. The CFX Expression Language tries to followthe following conventions:

1. Major words start with an upper case letter, while minor words such as prepositions and conjunctions areleft in lower case (for example, Mass Flow in).

2. Case is preserved for familiar names (for variables k or r), or for abbreviation RNG.

• User object names conventions can be chosen arbitrarily by you.

CCL Names DefinitionNames of singletons, types of object, names of objects, and names of parameters all follow the same rules:

• In simple syntax, a CCL name must be at least one character. This first character must be alphabetic; there maybe any number of subsequent characters and these can be alphabetic, numeric, space or tab.

• The effects of spaces in CCL names are:

• Spaces appearing before or after a name are not considered to be part of the name.

• Single spaces appearing inside a name are significant.

• Multiple spaces and tabs appearing inside a name are treated as a single space.

IndentationNothing in the file is sensitive to indentation, but indentation can be used for easier reading.

End of Line Comment CharacterThe # character is used for this. Any text to the right of this character will be treated as comments. Any charactersmay be used within comments.



Simple Syntax Details

Continuation CharacterIf a line ends with the character \, the following line will be linked to the existing line. There is no restriction onthe number of continuation lines.

Named ObjectsA named object consists of an object type at the start of a line, followed by a : and an object name. Subsequentlines may define parameters and child objects associated with this object. The object definition is terminated by thestring END on a line by itself.

Object names must be unique within the given scope, and the name must not contain an underscore.

Singleton ObjectsA singleton object consists of an object type at the start of a line, followed by a :. Subsequent lines may defineparameters and child objects associated with this object. The object definition is terminated by the string END on aline by itself.

The difference between a singleton object and a named object is that (after the data has been processed), a singletoncan appear just once as the child of a parent object. However, there may be several instances of a named object ofthe same type defined with different names.

ParametersA parameter consists of a parameter name at the start of a line followed by an = character followed by a parametervalue. A parameter may belong to many different object types. For example, U Velocity = 1.0 [m/s] maybelong to an initial value object and U Velocity = 2.0 [m/s] may belong to a boundary condition object.Both refer to the same definition of U velocity in the rules file.

ListsLists are used within the context of parameter values and are comma separated.

Parameter ValuesAll parameter values are initially handled as data of type String, and should first of all conform to the followingdefinition of allowed String values:

String• Any characters can be used in a parameter value.

• String values or other parameter type values are normally unquoted. If any quotes are present, they are consideredpart of the value. Leading and trailing spaces are ignored. Internal spaces in parameter values are preserved asgiven, although a given application is free to subsequently assume a space condensation rule when using thedata.

• The characters $ and # have a special meaning. A string beginning with $ is evaluated as a Power Syntaxvariable, even if it occurs within a simple syntax statement. This is useful for performing more complex PowerSyntax variable manipulation, and then using the result as part of a parameter or object definition. The appearanceof # anywhere in the CCL file denotes the start of a comment.

• The characters such as [, ],{ and } are special only if used in conjunction with $. Following a $, such charactersterminate the preceding Perl variable name.

• Other characters that might be special elsewhere in power syntax are escaped automatically when they appearin parameter values. For example, @, % and & are escaped automatically (i.e., you do not need to precede thesecharacters with the escape character \ when using them in parameter values).

• Parameter values can contain commas, but if the string is processed as a List or part of a List then the commasmay be interpreted as separators (see below under List data types).

Some examples of valid parameter values using special characters in power syntax are:

11




Estimated cost = \$500Title = Run\#1Sys Command = "echo 'Starting up Stress solver' ; fred.exe &"Pressure = $myArray[4]Option = $myHash{"foo"}Fuel = C${numberCatoms}H${numberHatoms}

Parameter values for data types other than String will additionally conform to one of the following definitions.

String ListA list of string items separated by commas. Items in a String List should not contain a comma unless containedbetween parentheses. One exception can be made if the String List to be is interpreted as a Real List (see below).Otherwise, each item in the String List follows the same rules as String data.

names = one, two, three, four

IntegerSequence of digits containing no spaces or commas. If a real is specified when an integer is needed, the real isrounded to the nearest integer.

Integer ListList of integers, separated by commas.

RealA single precision real number that may be specified in integer, floating point or scientific format, followed optionallyby a dimension. Units use the same syntax as CEL.

Expressions are allowed to include commas inside function call argument lists. Example usage:

a = 12.24a = 1.224E01 a = 12.24 [m s^-1]

A real may also be specified as an expression such as:

a = myvel^2 + ba = max(b,2.0)

Real ListList of reals, comma separated. Note that all items in the list must have the same dimensions. Items that are expressionsmay include commas inside function call argument lists, and the enclosed commas will be ignored when the list isparsed into individual items. Example usage:

a = 1.0 [m/s], 2.0 [m/s], 3.0 [m/s], 2.0*myvel, 4.0 [cm/s]

The list syntax 5*2.0 to represent 5 entries of the value 2.0 is not supported within CCL and hence within CFD-Post.

LogicalSeveral forms are acceptable: YES, TRUE, 1 or ON are all equivalent; NO or FALSE or 0 or OFF are all equivalent;initial letter variants Y, T, N, F are accepted (O is not accepted for On/Off); all case variants are accepted. Logicalstrings are also case insensitive (YeS, nO).

Logical ListList of logicals, separated by commas.

Escape CharacterThe \ character to be used as an escape character, for example, to allow $ or # to be used in strings.




Chapter 3. CFX Expression Language (CEL)CFX Expression Language (CEL) is an interpreted, declarative language that has been developed to enable CFXusers to enhance their simulations without recourse to writing and linking separate external Fortran routines.

You can use CEL expressions anywhere a value is required for input in ANSYS CFX.

CEL can be used to:

• Define material properties that depend on other variables.

• Specify complex boundary conditions.

• Add terms to the solved equations.

You can also monitor the value of an expression during the solution using monitor points.

ImportantThere is some CEL that works elsewhere in ANSYS CFX, but not in CFD-Post. Any expression createdin CFX-Pre and used as a Design Exploration output parameter could potentially cause fatal errors duringthe Design Exploration run, so you should create all expressions for Design Exploration output parametersin CFD-Post.

This chapter describes:

• CEL Fundamentals (p. 13)

• CEL Operators, Constants, and Expressions (p. 15)

• CEL Examples (p. 18)

• CEL Technical Details (p. 20)

CEL FundamentalsThe following topics will be discussed:

• Values and Expressions (p. 13)

• CFX Expression Language Statements (p. 14)

Values and ExpressionsCEL can be used to generate both values and expressions. Values are dimensional (that is, with units) or dimensionlessconstants. The simplest type of definition is the dimensionless value, for example:

b = 3.743

You can also specify a value with units, for example:

g = 9.81 [m s^-2]

The dimensions of the quantities of interest for CFD calculations can be written in terms of mass, length, time,temperature and angle. The concept of units is fundamental to the behavior of values and expressions.

Values can be used directly, or they can be used as part of an expression. For example, you can use an expressionto add two values together:

<Expr_1> = <Value_1> + <Value_2>

In this example, you may want to predefine <Value_1> and <Value_2>, but this is not required. However, inorder to add two quantities together, they must have the same dimension; that is, it is meaningful to add a quantityin inches to one expressed in meters, but it is not meaningful to add one expressed in kilograms to one in squarefeet.

Expressions can also be functions of other (predefined) expressions:

<Expr_2> = <Expr_1> + <Value_3>

13



Units follow the conventions in the rest of CFX, in that a calculation has a set of solution units (by default, SI units),and that any quantity can be defined either in terms of the solution units, or any other set of units with the correctform.

An expression does not have its own units string, but if it references quantities that have dimensions, these willdetermine the resulting units for the expression. For example, if an expression depends inversely on the square ofthe x coordinate, then it has implied dimensions of length to the power -2.

Using Locators in ExpressionsA CFX simulation has physics areas and mesh areas; physics areas are boundaries while mesh areas are regions.These two types of area can occupy completely different spaces in a simulation; however, there is no requirementthat area names be unique between physics and mesh. This can lead to ambiguities when you use these names inexpressions.

To avoid these ambiguities, ANSYS CFX first checks to see if "@<locator>" is a physics name; if this is not found,the name is checked in the list of mesh names. Thus if "in1" is both the name of a physics area and the name of amesh area, "@<locator>" is taken to indicate the physics area.

ANSYS CFX also has @REGION CEL syntax so that you can identify a named area as being a mesh area. Thusto identify the mesh area in1, you would use the syntax:

@REGION:in1

Note that if <locator> does not appear as a physics name or a mesh name, the expression fails.

CFX Expression Language StatementsThe CFX Expression Language is declarative. You declare the name and definition of the expression using expressionlanguage statements. The statements must conform to a predefined syntax that is similar to Fortran mathematicalstatements and to C statements for logical expressions.

The statement must consist of the following:

• a number, optionally with associated units. This defines a constant. Constants without units are termeddimensionless.

• for mathematical expressions, one or more references to mathematical constants, system variables, or existinguser variables, separated by + (addition), - (subtraction), * (multiplication), / (division) and (exponentiation),with optional grouping of these by parentheses. The syntax rules for these expressions are the same as those forconventional arithmetic.

• for logical expressions involving relational operators, one or more references to mathematical constants orresults from mathematical expressions, separated by <= (is less than or equal to), < (is less than), == (is equalto), != (is not equal to), > (is greater than) and >= (is greater than or equal to) with optional grouping of theseby parentheses.

• for logical expressions involving logical operators, one or more references to logical constants or results fromrelational operations separated by ! (negation), && (logical AND) and || (logical OR), with optional groupingby parentheses.

Use of ConstantsConstants do not need to be defined prior to being used in an expression. For example, you could choose to evaluatethe expression x + 5 [m]. Or, you could define a constant, b = 5 [m] and then create an expression x + b.

The logical constants are false and true. Results of logical expressions are expressed as 0 and 1 (correspondingto false and true, respectively).

The use of constants may be of benefit in generating complicated expressions or if you have several expressionsthat use the same constants.

Expression SyntaxAll numbers are treated as real numbers.

The precedence of mathematical operators is as follows (from highest to lowest):



CFX Expression Language Statements

• The power operator ^ as in x^y.

• The unary minus or negation operator - as in -x.

• Multiplication and division as in x*y/z.

• Addition and subtraction as in x+y-z.

Please note that, as of ANSYS CFX 10.0, the precedence of mathematical operators has been made consistent withstandard programming languages such as Fortran and C. Therefore, the power operator, which previously had lowerprecedence than unary minus, now has the highest precedence.

The precedence of logical and relational operators is as follows (from highest to lowest):

• The negation operator ! as in !x.

• The relational operators involving less than or greater than (<=, <, > and >=) as in x >= y.

• The relational operator is equal to and is not equal to (== and !=) as in x != y.

• The logical AND operator (&&) as in x && y.

• The logical OR operator (||) as in x || y.

Multiple-Line ExpressionsIt is often useful, particularly with complex expressions, to use more than one line when creating your expression.CFX allows you to use multiple lines to generate an expression, provided each line is separated by an appropriateoperator.

For example, you may have an equation, A + B/C, that consists of three complex terms, A, B, and C. In this case,you could use three lines to simplify creating the expression:

A +B/ C

Note that the operator may be used at the end of a line (A +) or at the beginning of a line (/ C). You do not need toenter the operator twice.

Once the expression has been created, it will appear in the Existing Definitions list box as if it were generated ona single line (A + B/C).

CEL Operators, Constants, and ExpressionsThe following topics are discussed:

• CEL Operators (p. 15)

• Conditional if Statement (p. 16)

• CEL Constants (p. 17)

• Using Expressions (p. 17)

CEL OperatorsCFX provides a range of mathematical, logical and operational operators as built-in functions to help you createcomplex expressions using the Expression details view.

15



CEL Operators, Constants, and Expressions

Table 3.1. CEL operators

Result'sDimensions

Operands' Values(Approx)

SecondOperand'sDimensions [y]

First Operand'sDimensions [x]

Operator

[x]AnyAny-x

[x]Any[x]Anyx+y

[x]Any[x]Anyx-y

[x]*[y]AnyAnyAnyx*y

[x]/[y]≠y 0AnyAnyx/y

[x]^yAnyaDimensionlessAnyx^y (if y is a simple,constant, integerexpression)

[x]^yx > 0DimensionlessAnyx^y (if y is anysimple, constant,expression)

Dimensionlessx > 0DimensionlessDimensionlessx^y (if y is not simple& constant)

Dimensionless0 or 1Dimensionless!x

Dimensionless0 or 1[x]Anyx <= y

Dimensionless0 or 1[x]Anyx < y

Dimensionless0 or 1[x]Anyx > y

Dimensionless0 or 1[x]Anyx >= y

Dimensionless0 or 1[x]Anyx == y

Dimensionless0 or 1[x]Anyx != y

Dimensionless0 or 1DimensionlessDimensionlessx && y

Dimensionless0 or 1DimensionlessDimensionlessx || y

aFor y < 0, x must be non-zero.

Conditional if StatementCEL supports the conditional if statement using the following syntax:

if( cond_expr, true_expr, false_expr )

where:

• cond_expr: is the logical expression used as the conditional test

• true_expr: is the mathematical expression used to determine the result if the conditional test is true.

• false_expr : is the mathematical expression used to determine the result if the conditional test is false.

NoteThe expressions true_expr and false_expr are always evaluated independent of whether theevaluation of cond_expr is true or false. As a consequence, a conditional statement cannot beused to avoid division by zero as in if( x>0, 1/x, 1.0). In this case, when x=0.0, a division



Conditional if Statement

by zero will still occur because the expression 1/x is evaluated independent of whether x>0 is satisfiedor not.

CEL ConstantsRight-click in the Expression details view to access the following useful constants when developing expressions:

Table 3.2. CEL Constants

DescriptionUnitsConstant

Universal Gas Constant: 8.314472J K^-1 mol^-1R

6.02214199E+23mol^-1avogadro

1.3806503E-23J K^-1boltzmann

2.99792458E+08m s^-1clight

Constant: 2.7182817Dimensionlesse

Constant: 1.60217653E-19A secharge

1./(clight*clight*mupermo)epspermo

Acceleration due to gravity: 9.8066502m s^-2g

4*pi*1.E-07N A^-2mupermo

Constant: 3.141592654Dimensionlesspi

6.62606876E-34J splanck

5.670400E-08W m^-2 K^-4stefan

Using ExpressionsThe interaction with CEL consists of two phases:

• a definition phase, and,

• a use phase.

The definition phase consists of creating a set of values and expressions of valid syntax. The purpose of theExpression details view is to help you to do this.

Use of Offset TemperatureWhen using temperature values in expressions, it is generally safer to use units of [K] only. When units are usedthat posses an offset (for example, [C]), they are converted internally to [K]. For terms that have temperature to thepower of unity, any unit conversion will include the offset between temperature scales. However, in all other casesthe offset is ignored since this is usually the most appropriate behavior. You should therefore take care whenspecifying an expression involving non-unit powers of temperature. For example, each of the expressions below isequivalent:

Temperature = 30 [C]Temperature = 303.15 [K]Temperature = 0 [C] + 30 [K]Temperature = 273.15 [K] + 30 [K]

These are only equivalent because all units are to the power of unity and units other than [K] appear no more thanonce in each expression. The following expression will not produce the expected result:

17



CEL Constants

Temperature = 0 [C] + 30 [C]

This is equivalent to 576.30 [K], since each value is converted to [K] and then summed. The two expressionbelow are equivalent (as expected) because the offset in scales is ignored for non-unit powers of temperature:

Specific Heat = 4200 [J kg^-1 C^-1]Specific Heat = 4200 [J kg^-1 K^-1]

CEL ExamplesThe following examples are included in this section:

• Example: Reynolds Number Dependent Viscosity (p. 18)

• Example: Feedback to Control Inlet Temperature (p. 19)

Example: Reynolds Number Dependent ViscosityIn this example it is assumed that some of the fluid properties, including the dynamic viscosity, are not known.However the Reynolds number, inlet velocity and a length scale are known. The flow is compressible and thereforethe density is variable.

Given this information it is possible to calculate the fluid dynamic viscosity based on the Reynolds number. TheReynolds number is given by:

=Re ρU Lμ

where ρ is density, U a velocity scale, L a length scale and μ the dynamic viscosity. The velocity scale is taken asthe inlet velocity, the length scale as the inlet width and the density is calculated as the average density over theinlet area.

The LIBRARY section of the CCL (CFX Command Language) file appears as follows:

LIBRARY : CEL : EXPRESSIONS : Re = 4.29E6 [ ] Vel = 60 [m s^-1] L=1.044[m] Visc=areaAve(density)@in*Vel*L/Re END END MATERIAL : Air Ideal Gas Option = Pure Substance PROPERTIES : Option = Ideal Gas Molar Mass = 2.896E1 [kg kmol^-1] Dynamic Viscosity = Visc Specific Heat Capacity = 1.E3 [J kg^-1 K^-1] Thermal Conductivity = 2.52E-2 [W m^-1 K^-1] END ENDEND

This shows that four CEL expressions have been created. The first three expressions define constant values that areused in the Visc expression. The Visc expression calculates the dynamic viscosity based on the equation forReynolds number given above. Within the expression the function areaAve(density)@in is used to evaluatethe average density at the inlet.

The Visc expression can now be used to replace the value of Dynamic Viscosity in the MATERIAL >PROPERTIES section.



CEL Examples

Example: Feedback to Control Inlet TemperatureIn this example a feedback loop is used to control the outlet temperature by varying the temperature at an inlet. Toillustrate the example consider the geometry shown below:

Figure 3.1. Temperature feedback loop

Fluid from a main and a side inlet enter at temperatures of 275 K and 375 K respectively. The temperature of thefluid entering from the third inlet depends on the outlet temperature. When the outlet temperature is greater than325 K, the fluid from the third inlet is set to 275 K. When the outlet temperature is less than 325 K, the fluid fromthe third inlet is set to 375 K. In addition an expression is used to set the dynamic viscosity to be a linear functionof temperature.

The LIBRARY section of the .ccl (CFX Command Language) file appears as follows. Note that the “\” characterindicates a line continuation in CCL.

LIBRARY: MATERIAL: Water at STP Modified Option = Pure Substance PROPERTIES: Option = General Fluid Density = 9.999E2 [kg m^-3] Dynamic Viscosity = VisT Specific Heat Capacity = 4.21E3 [J kg^-1 K^-1] Thermal Conductivity = 5.69E-1 [W m^-1 K^-1] END # PROPERTIES END # MATERIAL Water at STP Modified CEL: EXPRESSIONS: Tupper = 375.0 [ K ] # Upper temp. Tlower = 275.0 [ K ] # Lower temp. Visupper = 0.000545 [ N s m^-2 ] # Vis. at Tupper Vislower = 0.0018 [ N s m^-2 ] # Vis. at Tlower VisT = Vislower+(Visupper-Vislower)*(T-Tlower)/ \ (Tupper-Tlower) # Vis.-Temp. relationship Tm=(Tupper+Tlower)/2 Tout=areaAve(Water at STP Modified.T)@outlet Tcontrol=Tlower*step((Tout-Tm)/1[K]) \ +Tupper*step((Tm-Tout)/1[K]) END # EXPRESSIONS END # CELEND # LIBRARY

The first four expressions, Tupper, Tlower, Visupper and Vislower are simply constant values to definetemperature and viscosity values. The expression VisT produces a linear function for the dynamic viscosity takinga value of Visupper at Tupper and a value of Vislower at Tlower. The expression Tm sets the desired valueof the outlet temperature. In this case it is set to a mean value of the two inlet temperatures.

19



Example: Feedback to Control Inlet Temperature

Tout calculates the outlet temperature using the areaAve function.

Finally the expression Tcontrol is used to set the temperature of the third inlet. Two step functions are used sothat the temperature is equal to Tlower when Tout-Tm is positive (that is, the outlet temperature is greater thanTm), and is equal to Tupper when Tout-Tm is positive.

Examples: Using Expressions in ANSYS CFD-PostThe first example is a single-valued expression that calculates the pressure drop through a pipe. The names of inletand outlet boundaries are “inlet” and “outlet”.

Create a new expression named “dp”:

dp = massFlowAve(Pressure)@inlet – massFlowAve(Pressure)@outlet

When you click Apply, the value is shown below the editor.

TipAlternatively, type the expression in a table cell and prefix with ‘=’ sign. The cell displays the resultwhen you click outside of the cell.

The second example is a variable expression that plots the pressure coefficient variation on a surface or a line:

1. Click the Expressions tab, then right-click in the Expressions area and select New.

2. Create these three expressions:

RefPressure = 100000 [Pa]dynHead = 0.5 * areaAve(Density)@inlet * areaAve(Velocity)@inlet^2cpExp = (Pressure - RefPressure)/dynHead

3. Click the Variables tab, then right-click and select New.

4. Create a user variable defined by cpExp.

5. Select Insert > Location > Line and use the Details view to position the line in the simulation.

From the Details view Color tab, plot the user variable on a surface or a line (just as you would with any othervariable).

CEL Technical DetailsCEL is a byte code compiled language. Compiled languages, such as Fortran, rely on a translation program toconvert them into the native machine language of the host platform. Interpreted languages are of two types: thefully interpreted languages such as the UNIX C shell, and the byte code compiled languages such as CEL. Withbyte codes, host machines are loaded with a client program (written in a compiled language and compiled for thatmachine architecture) that interprets the byte stream. The advantage of the byte code is that they can be the sameon all host platforms, obviating the need for platform dependent codes.

Since the byte codes are interpreted, there is no need to re-link executable programs to perform a different calculation.Furthermore, many of the problems encountered by writing and linking in separate routines, for instance in C orFortran, are averted, and the time taken to set up and debug complicated problems reduced considerably.

The link between CEL and the CFX-Solver is accomplished through an internal program called genicode. Genicodegenerates intermediate code from your CEL definitions and writes to a file that is then interpreted by the CFX-Solverduring the solution process.



Examples: Using Expressions in ANSYS CFD-Post

Chapter 4. Functions in ANSYS CFXThis chapter describes predefined functions in ANSYS CFX:

• CEL Mathematical Functions (p. 21)

• Quantitative CEL Functions in ANSYS CFX (p. 23)

• Functions Involving Coordinates (p. 25)

• CEL Functions with Multiphase Flow (p. 25)

• Quantitative Function List (p. 26)

CEL Mathematical FunctionsThe following mathematical functions are available for use with all CEL expressions.

NoteIn the Function column in the table below, [a] denotes any dimension of the first operand.

21



Table 4.1. Standard Mathematical CEL Functions

Result's DimensionsOperand's ValuesFunction

[a]Anyabs( [a] )

Radians− ≤ ≤x1 1acos( [ ] )

Radians− ≤ ≤x1 1asin( [ ] )

RadiansAnyatan( [ ] )a

RadiansAnyatan2( [a], [a] )[b]

Dimensionless≤n0besselJ( [ ], [ ] )b

Dimensionless≤n0besselY( [ ], [ ] )b

DimensionlessAnycos( [radians] )

DimensionlessAnycosh( [ ] )

DimensionlessAnyexp( [ ] )

Same as OperandAnyint([ ])c

Dimensionless<x0loge( [ ] )d

Dimensionless<x0log10( [ ] )e

[a]Anymin( [a], [a] )

[a]Anymax( [a], [a] )

[a]Anymod( [a], [a] )f

Same as OperandAnynint([ ])g

DimensionlessAnysin( [radians] )

DimensionlessAnysinh( [ ] )

[a]^0.5≤x0sqrt( [a] )

DimensionlessAnystep( [ ] ) h

DimensionlessAnytan( [radians] )i

DimensionlessAnytanh( [ ] )

aatan does not determine the quadrant of the result, but atan2 does.bThe value of the first dimensionless operand n, also referred to as the order of the Bessel function, must be an integer (n=0, 1, 2, ....). The secondargument is a dimensionless real number.c The int function converts the argument to solution units and then truncates the result to its integer part.

Examples:

int(1) = 1

int(2.5) = 2

int(-3.1) = -3

int(-4.8) = -4dln(x) is valid as an alias for loge(x)elog(x) is valid as an alias for log10(x)fmod(x, y) returns the remainder on dividing x by y; the function is not defined for y = 0.



CEL Mathematical Functions

gThe nint function is defined as:

int(x + 0.5) if x >= 0

int(x - 0.5) if x < 0

See the implementation of int( ) function in the table above.

Examples:

nint(2.6) = 3

nint(2.5) = 3

nint(2.4) = 2

nint(1) = 1

nint(-1) = -1

nint(-2.4) = -2

nint(-2.5) = -3

nint(-2.6) = -3hstep(x) is 0 for negative x, 1 for positive x and 0.5 for x=0. x must be dimensionless.itan(x) is undefined for x=nπ/2, where n=1, 3, 5, ...

Quantitative CEL Functions in ANSYS CFXCEL expressions can incorporate specialized functions that are useful in CFD calculations. All CEL functions aredescribed in Quantitative Function List (p. 26). For a description of the full CFX Expression Language, see CFXExpression Language (CEL) (p. 13).

ImportantYou must use consistent units when adding, subtracting, or comparing values.

There are some differences between CEL functions in CFX-Pre and CFX-Solver and those in CFD-Post.For details, see below.

The syntax used for calling these functions when used within CEL expressions is:

[<Phase_Name>.][<Component_Name>.]<Function>([<Operand>])@<Location>

where:

• Terms enclosed in square brackets [ ] are optional and terms in angle brackets< > should be replaced withthe required entry.

• <Phase_Name>: specifies a valid name of a phase. The phase can be fluid, particle, solid, fluid pair, orpolydispersed fluid. For multi-phase cases in CFX-Pre, if the phase name is not specified in the <Operand>,then the phase name associated with the domain, subdomain, domain boundary, initialization or function inwhich the operand is being evaluated will be used. For multi-phase cases in CFX-Pre, a discussion of the handlingof the phase name when it is not used to qualify (prepended to) <Function> and/or <Operand> can befound in CEL Functions with Multiphase Flow (p. 25). For multi-phase cases in CFD-Post, if the phase nameis not specified then the bulk quantity (if available for the CFX-Solver Results file) is used.

• <Component_Name>: specifies a valid name of a component material, size group, or reaction

• <Function>: specifies the CEL function to evaluate. See Quantitative Function List (p. 26). The functioncan be further qualified by appending _Coordinate_Direction. In CFX-Pre, if the coordinate frame isnot specified (in _Coordinate_Direction ) then the function will use the coordinate frame associatedwith the object (such as for a material, domain, subdomain, domain boundary, source point, monitor point,initialization, reference location or spark ignition object) in which it is being invoked.

• <Coordinate_Direction>: specifies a particular coordinate direction. The syntax of the coordinatedirection is [x|y|z][_<Coordinate_Frame>] where the coordinate frame can be the global coordinateframe or any user defined coordinate frame. In CFD-Post, if the coordinate frame is not specified then the globalframe is used. See Coordinate Frame Command (p. 174) in ANSYS CFD-Post Standalone: User's Guide, fordiscussion of creating a coordinate frame in CFD-Post.

• <Operand>: specifies the argument of the function (if required). The operand can be either a valid mathematicalCEL expression (only in CFD-Post) or specified using the following general variable syntax:

23



Quantitative CEL Functions in ANSYS CFX

[<Phase_Name>.][<Component_Name>.]<Variable_Name>[.<Variable_Operator>][.Difference]

In CFX-Pre the operand cannot be a CEL expression or any operand qualified by <Variable_Operator>.However, you can create an Additional Variable based on any expression and then use the Additional Variableas the operand . The operand always uses the conservative values unless the Boundcon variable operator isspecified (for details, see Data Acquisition Routines in the ANSYS CFX-Solver Modeling Guide). The operandmust be valid for the physical models being used over the entire location. For example, if the location spansfluid and solid domains, then the operand cannot be Pressure.

For some functions the operand must be left blank as in area()@Inlet.

In CFD-Post, difference variables created during case comparison are appended by .Difference.

• <Variable_Name>: specifies the base name of the variable. You can use the short or long form for variablenames. In CFX-Pre the variable name can be further qualified by appending _<Coordinate_Direction>.This is useful for specifying a particular component of a vector or tensor, for exampleVelocity_y_myLocalFrame. In CFX-Pre, if the variable name corresponds to that of a component of avector or a tensor and coordinate frame is not prescribed (as part of the coordinate direction) then the globalcoordinate frame is used. An exception applies for the position vector x, y, z ( or r,theta,z) components,which are always local, see Functions Involving Coordinates (p. 25).

• <Variable_Operator> specifies the name of the variable operator. The syntax for specifying the variableoperator is [Gradient|Curl|Trnav|Trnsdv|Trnmin|Trnmax|Boundcon|<Derived>]. All butthe <Derived> operator are available in CFX-Pre and CFD-Post, provided they are available in the CFX-SolverResults file, see Data Acquisition Routines in the ANSYS CFX-Solver Modeling Guide. The <Derived>variable operator is available in CFD-Post, for example Absolute Helicity derived for use with VortexCores, see Vortex Core Region (p. 147) in ANSYS CFD-Post Standalone: User's Guide. In CFX-Pre the variableoperator can be further qualified by appending _<Coordinate_Direction>.

• <Location>: specifies the location over which the function is to be applied. The syntax of location is:

[Case:<Case_Name>.][REGION:]<Location_Name>

The case syntax [Case:<Case_Name>.] is only available in CFD-Post and is used when multiple cases areloaded to indicate the name of the desired case.

In CFX-Pre [<Location_Name>] must be a domain boundary, domain, subdomain, or, primitive or compositemesh region. If the location name of a mesh region is the same as the name of a named boundary, domain orsubdomain, then the mesh location name must be prepended by REGION:.

In CFD-Post [<Location_Name>] can be any loaded or user-defined location (for example, a point, domainboundary, plane, mesh region etc.). The syntax REGION:<Region Name> can also be used in CFD-Post torefer to any mesh region. If a mesh region is present with the same name as, for example, a domain boundary,then the mesh region is imported into CFD-Post with a Region suffix. For example, if there is both a domainboundary and a mesh region called in1 in the CFX-Solver Results file, then in CFD-Post the mesh region willappear in CFD-Post as in1 Region. The syntax in1 will refer to the domain boundary, and either of in1Region or REGION:in1 can be used to refer to the mesh region as desired.

NoteYou cannot use a composite region that consists of a mixture of 2D and 3D regions.



Quantitative CEL Functions in ANSYS CFX

Table 4.2. Examples of the Calling Syntax for an Expression

This results in the area-weighted average of pressureon the boundary named Inlet.

areaAve(p)@Inlet

This results in the area of a 2D mesh region namedmyCompositeMeshRegion.

area()@REGION:myCompositeMeshRegion

This syntax is appropriate only for CFD-Post.areaAve(Pressure - 10000 [Pa])@outlet

area_x()@inlet

Water at RTP.force_z()@Default

Functions Involving CoordinatesThe CEL variables x, y, z, r and theta, representing the local coordinates, cannot be used as the variable. However,the variables xGlobal, yGlobal and zGlobal can be used. For example, the following is a valid expressiondefinition:

z*areaAve(xGlobal)@inlet

CEL Functions with Multiphase FlowNoteThese functions are available in CFX-Pre and CFX-Solver without restrictions, and in CFD-Post withthe restriction that you cannot use short names.

If the function is fluid-specific, various behaviors are possible depending on the function type:

• For massFlow and massFlowAve, if the phase name is not specified for the function, then the bulk massflows will be used. See cases 1 to 7 in the table below.

• For other fluid-specific functions:

• if a fluid-specific operand is specified and no fluid is specified for the function, then the fluid specified forthe operand will be assumed for the function as well. See case 8 in the table below.

• if the function is specified and no fluid is specified for the operand, then the fluid specified for the functionwill be assumed for the operand as well. See cases 7 and 9 in the table below.

• If both the function or operand are fluid-specific, and a phase name is not given for either, the solver will stopwith an error. See case 10 in the table below.

25



Functions Involving Coordinates

Table 4.3. CEL Multiphase Examples

BehaviorCEL Function - MultiphaseCase

Bulk mass flow rate through inletmassFlow()@inlet1

Air mass flow rate through inletAir.massFlow()@inlet2

Bulk mass flow averaged pressure on inletmassFlowAve(Pressure)@inlet3

Air mass flow averaged pressure on inletAir.massFlowAve(Pressure)@inlet4

Bulk mass flow averaged air volume fraction oninlet

massFlowAve(Air.VolumeFraction)@inlet

5

Air mass flow averaged air volume fraction on inletAir.massFlowAve(Air.VolumeFraction)@inlet

6

Same as Air.massFlowAve(Air.VolumeFraction) @ inlet

Air.massFlowAve(VolumeFraction)@inlet

7

Same as Air.massInt(Air.VolumeFraction) @ domain1

massInt(Air.VolumeFraction)@domain1

8

Same as Air.massInt(Air.VolumeFraction) @ domain1

Air.massInt(VolumeFraction)@domain1

9

Error because no fluid specifiedmassFlowAve(VolumeFraction)@inlet

10

Quantitative Function ListThe available quantitative functions are outlined in the sections that follow.

In the table that follows, <Expression> in CFD-Post means any expression; however, in CFX-Pre and CFX-Solver<Expression> means "Additional Variable Expression”.

The behavior of the functions in the table below depends in the type of <Location>. Typically:

• on a domain the functions use vertex values for the operand,

• on a subdomain the functions use element values for the operand,

• on a boundary the functions use conservative values for the operand unless this is overriden by the Boundconvariable operator in CFX-Pre,

• on user locations in CFD-Post the functions use values interpolated from nodal values.



Quantitative Function List

Table 4.4. CEL Functions in CFX-Pre/CFX-Solver and in CFD-Post

AvailabilityOperationFunction Name and Syntax<required> [<optional>]

AllArea of a boundary or interface.area( )

Supports @<Location>

See area (p. 30).

AllaThe (signed) component of the normal area vector in thelocal x, y or z direction. The normal area vectors are

area_x[_<Coord Frame>]( )

area_y[_<Coord Frame>]( )always directed out of the domain, therefore you may

area_z[_<Coord Frame>]( ) obtain positive or negative areas depending on theorientation of your domain and the boundary you areoperating on. The area of a closed surface will always bezero.


AllArea-weighted average of <Expression> on a boundary.areaAve(<Expression>)


See areaAve (p. 31).

CFD-PostThe (signed) component of the normal area vectorweighted average in the local x, y or z direction. The

areaAve_x[_<Coord Frame>]( )

areaAve_y[_<Coord Frame>]( )normal area vectors are always directed out of the domain,

areaAve_z[_<Coord Frame>]( ) therefore you may obtain positive or negative areasdepending on the orientation of your domain and theboundary you are operating on. The area of a closedsurface will always be zero.


AllArea-weighted integral of <Expression> on a boundary.areaInt(<Expression>)

The areaInt function projects the location onto a planenormal to the specified direction (if the direction is notset to None) and then performs the calculation on theprojected location (the direction specification can also beNone). The direction of the normal vectors for thelocation is important and will cancel out for surfaces suchas closed surfaces.


See areaInt (p. 31).

AllThe (signed) component of the normal area vectorweighted integral in the local x, y or z direction. The

areaInt_x[_<Coord Frame>]( )

areaInt_y[_<Coord Frame>]( )normal area vectors are always directed out of the domain,

areaInt_z[_<Coord Frame>]( ) therefore you may obtain positive or negative areasdepending on the orientation of your domain and theboundary you are operating on. The area of a closedsurface will always be zero.


AllArithmetic average of <Expression> over nodes withina domain or subdomain.

ave(<Expression>)


See ave (p. 32).

27





AllCounts the number of evaluation points (nodes) on thenamed region.

See count (p. 33).

count( )

AllCounts the number of nodes at which the logicalexpression evaluates to true.


See countTrue (p. 33).

countTrue(<Expression>)

AllThe magnitude of the force vector on a boundary.

Supports [<Phase>.], @<Location>

See force (p. 34).

force( )

CFD-PostThe length of the normalized force on a curve in thespecified direction.


See forceNorm (p. 35).

forceNorm [_<Axis>[_<CoordFrame>]]( )

AllaThe (signed) component of the force vector in the localx, y or z direction.


force_x[_<Coord Frame>]( )

force_y[_<Coord Frame>]( )

force_z[_<Coord Frame>]( )

CFX-Pre,CFX-Solver

Similar to the subdomain variable, but allows a specific2D or 3D location to be given.


See inside (p. 35).

inside()

CFD-PostLength of a curve.


See length (p. 36).

length()

CFD-PostLength-weighted average.


See lengthAve (p. 36).

lengthAve(<Expression>)

CFD-PostLength-weighted integration.


See lengthInt (p. 37).

lengthInt(<Expression>)

CFX-Pre,CFX-Solver

The total mass within a domain or subdomain. This isfluid-dependent.


See mass (p. 37).

mass()

CFX-Pre,CFX-Solver

Mass-weighted average of <Expression> on a domain orsubdomain.


See massAve (p. 37).

massAve(<Expression>)





AllMass flow through a boundary.


See massFlow (p. 37).

massFlow()

AllMass flow weighted average of <Expression> on aboundary.


See massFlowAve (p. 38).

massFlowAve(<var>)

AllAbsolute mass flow weighted average of <Expression>on a boundary.


See massFlowAveAbs (p. 39).

massFlowAveAbs(<var>)

AllMass flow weighted integration of <Expression> on aboundary.


See massFlowInt (p. 40).

massFlowInt(<var>)

CFX-Pre,CFX-Solver

The mass-weighted integration of <Expression> withina domain or subdomain.


See massInt (p. 41).

massInt(<Expression>)

AllMaximum Value of <Expression> within a domain orsubdomain.


See maxVal (p. 41).

maxVal(<Expression>)

AllMinimum Value of <Expression> within a domain orsubdomain.


See minVal (p. 41).

minVal(<Expression>)

AllReturns the value of the specified variable on the specifiedPoint locator.


See probe (p. 42).

probe(<Expression>)

CFX-Pre/CFX-SolverRMS average of <Expression> within a 2D domain.


See rmsAve (p. 42).

rmsAve(<Expression>)

AllSum of <Expression> over all domain or subdomainvertices.


See sum (p. 42).

sum(<Expression>)

29





AllMagnitude of the torque vector on a boundary.


See torque (p. 43).

torque( )

CFX-Pre,

CFX-SolveraThe (signed) components of the torque vector about thelocal x, y, or z coordinate axis.


torque_x[_<Coord Frame>]()

torque_y[_<Coord Frame>]()

torque_z[_<Coord Frame>]()

AllThe total volume of a domain or subdomain.


See volume (p. 43).

volume( )

AllVolume-weighted average of <var> on a domain.


See volumeAve (p. 43).

volumeAve(<Expression>)

AllVolume-weighted integration of <var> within a domainor subdomain.


See volumeInt (p. 44).

volumeInt(<Expression>)

aSee the definition for [_<Coordinate_ Direction>]] in Quantitative CEL Functions in ANSYS CFX (p. 23)

areaThe area function is used to calculate the area of a 2D locator.

area[_<Axis>[_<Coord Frame>] ]()@<Location>

where:

• <Axis> is x, y, or z

• <Coord Frame> is the coordinate frame

• <Location> is any 2D region (such as a boundary or interface).

An error is raised if the location specified is not a 2D object. If an axis is not specified, the total area of the locationis calculated.

area()@Isosurface1 calculates the total area of the location, and Isosurface1.area_y()@Isosurface1calculates the projected area of Isosurface1 onto a plane normal to the Y-axis.

Tools > Command Editor Example

>calculate area, <Location>, [<Axis>]

The specification of an axis is optional. If an axis is not specified, the value held in the object will be used. Tocalculate the total area of the location, the axis specification should be left blank (that is, type a comma after thelocation specification).

>calculate area, myplane calculates the area of the locator myplane projected onto a plane normal tothe axis specification in the CALCULATOR object.

>calculate area, myplane, calculates the area of the locator myplane. Note that adding the commaafter myplane removes the axis specification.



area

Tools > Function Calculator ExampleThe following example will calculate the total area of the locator Plane1:

Function: area, Location: Plane1.

areaAveThe areaAve function calculates the area-weighted average of an expression on a 2D location. The area-weightedaverage of a variable is the average value of the variable on a location when the mesh element sizes are taken intoaccount. Without the area weighting function, the average of all the nodal variable values would be biased towardsvariable values in regions of high mesh density.

areaAve[_<Axis>[_<Coord Frame>] ](<Expression>)@<Location>

where:


• <Coord Frame> is available in CFD-Post only

• <Expression> is an expression

• <Location> is any 2D region (such as a boundary or interface). An error is raised if the location specified isnot a 2D object.

To calculate the pressure coefficient Cp, use:

(Pressure - 1[bar])/(0.5*Density*(areaAve(Velocity)@inlet)^2)

You can create an expression using this, and then create a user variable using the expression. The user variable canthen be plotted on objects like any other variable.


>calculate areaAve, <Expression>, <Location>, <Axis>

Tools > Function Calculator Examples• This example will calculate the average magnitude of Velocity on outlet.

Function: areaAve, Location: outlet, Variable: Velocity.

Note that flow direction is not considered because the magnitude of a vector quantity at each node is calculated.

• You can use the scalar components of Velocity (such as Velocity u) to include a directional sign. Thisexample will calculate the area-weighted average value of Velocity u, with negative values of Velocityu replaced by zero. Note that this is not the average positive value because zero values will contribute to theaverage.

Function: areaAve, Location: outlet, Variable: max(Velocity u, 0.0[m s^-1]).

areaIntThe areaInt function integrates a variable over the specified 2D location. To perform the integration over thetotal face area, select the None option from the Axis drop-down menu. If a direction is selected, the result is anintegration over the projected area of each face onto a plane normal to that direction. Each point on a location hasan associated area which is stored as a vector and therefore has direction. By selecting a direction in the functioncalculator, you are using only a single component of the vector in the area-weighting function. Because thesecomponents can be positive or negative, depending on the direction of the normal on the location, it is possible forareas to cancel out. An example of this would be on a closed surface where the projected area will always be zero(the results returned will not in general be exactly zero because the variable values differ over the closed surface).On a flat surface, the normal vectors always point in the same direction and never cancel out.

31



areaAve

areaInt[_<Axis>[_<Coord Frame>] ](<Expression>)@<Location>

where:

• <Axis> is x, y, or z.

Axis is optional; if not specified the integration is performed over the total face area. If axis is specified, thenthe integration is performed over the projected face area. A function description is available.

• <Coord Frame> is the coordinate frame.

• <Location> is any 2D region (such as a boundary or interface). An error is raised if the location specified isnot a 2D object.

areaInt_y_Frame2(Pressure)@boundary1 calculates the pressure force acting in the y-direction of thecoordinate frame Frame2 on the locator boundary1. This differs from a calculation using the force function,which calculates the total force on a wall boundary (that is, viscous forces on the boundary are included).


>calculate areaInt, <Expression>, <Location>, [<Axis>]

Axis is optional. If it is not specified, the value held in the object will be used. To perform the integration over thetotal face area, the axis specification should be blank (that is, type a comma after the location name). A functiondescription is available in areaInt (p. 31).

Tools > Function Calculator Examples• This example integrates Pressure over Plane 1. The returned result is the total pressure force acting on

Plane 1. The magnitude of each area vector is used and so the direction of the vectors is not considered.

Function: areaInt, Location: Plane 1, Variable: Pressure, Direction: None

• This example integrates Pressure over the projected area of Plane 1 onto a plane normal to the X-axis.The result is the pressure force acting in the X-direction on Plane 1. This differs slightly from using the forcefunction to calculate the X-directional force on Plane 1. The force function includes forces due to the advectionof momentum when calculating the force on an internal arbitrary plane or a non-wall boundary (inlets, etc.).

Function: areaInt, Location: Plane 1, Variable: Pressure, Direction: Global X.

aveThe ave function calculates the arithmetic average (the mean value) of a variable or expression on the specifiedlocation. This is simply the sum of the values at each node on the location divided by the number of nodes. Resultswill be biased towards areas of high nodal density on the location. To obtain a mesh independent result, you shoulduse the lengthAve, areaAve, volumeAve or massFlowAve functions.

ave(<var|Expression>)@<Location>

where:

• <var|Expression> is a variable or a logical expression

• <Location> is any 3D region (such as a domain or subdomain).

The ave function can be used on point, 1D, 2D, and 3D locations.

ave(Yplus)@Default calculates the mean Yplus values from each node on the default walls.



ave


>calculate ave, <var|Expression>, <Location>

NoteTo obtain a mesh-independent result, you should use the lengthAve, areaAve, volumeAve ormassFlowAve functions.

The average of a vector value is calculated as an average of its magnitudes, not the magnitude of component averages.As an example, for velocity:

(Eq. 4.1)= +v v vave 2

1 2

where

(Eq. 4.2)= + +v v v v( )i x i y i z i,2

,2

,2

Tools > Function Calculator ExampleThis example calculates the mean temperature at all nodes in the selected domain.

Function: ave, Location: MainDomain, Variable: Temperature.

countThe count function returns the number of nodes on the specified location.

count()@<Location>

where:

• <Location> is valid for point, 1D, 2D, and 3D locations.

count()@Polyline1 returns the number of points on the specified polyline locator.


>calculate count, <Location>

Tools > Function Calculator ExampleThis example returns the number of nodes in the specified domain.

Function: count, Location: MainDomain.

countTrueThe countTrue function returns the number of mesh nodes on the specified region that evaluate to “true”, wheretrue means greater than or equal to 0.5. The countTrue function is valid for 1D, 2D, and 3D locations.

countTrue(<Expression>)@<Location>

where <Expression> is:

• In CFD-Post, an expression that contains the logical operators =, >, <, <=, or >=.

• In CFX-Solver, an Additional Variable that you define. For example:

TemperatureLE = Temperature > 300[K]

countTrue(TemperatureLE)@Polyline1 returns the number of nodes on the specified polyline locatorthat evaluate to true.

33



count

Tools > Command Editor ExamplesIn CFD-Post:

>calculate countTrue(Temperature > 300[K]), Domain1

In CFX-Solver:

>calculate countTrue(TemperatureLE), Domain1

Tools > Function Calculator ExampleThis example returns the number of nodes that evaluate to “true” in the specified domain.

Function: countTrue, Location: MainDomain, Expression: Temperature > 300[K].

forceThis function returns the force exerted by the fluid on the specified 2D locator in the specified direction.

[<Phase>.]force[_<Axis>[_<Coord Frame>] ]()@<Location>

where:

• [<Phase>.] is an optional prefix that is not required for single-phase flows. For details, see CEL Functionswith Multiphase Flow (p. 25).


• <Coord Frame> is the coordinate frame

• <Location> is any 2D region (such as a boundary or interface).

Force calculations on boundaries require additional momentum flow data.

Water at RTP.force_x()@wall1 returns the total force in the x-direction acting on wall1 due to the fluidWater at RTP.

The force on a boundary is calculated using momentum flow data from the results file, if it is available. The resultcan be positive or negative, indicating the direction of the force. For non-boundary locators, an approximate forceis always calculated.

CFD-Post calculates the approximate force as follows:

• If the locator is a wall boundary, the force is equal to the pressure force.

• For all other locators, the force is equal to the pressure force plus the mass flow force (due to the advection ofmomentum).

• In all cases, if wall shear data exists in the results file, the viscous force is added to the calculated force.

The force function enables you to select the fluids to use when performing your calculation. The result returnedis the force on the locator due to that fluid/those fluids. Because the pressure force is the same at each node irrespectiveof the choice of fluids, the only difference is in the viscous forces (on wall boundaries) or the mass flow forces.

It is important to note that forces arising as a result of the reference pressure are not included in the force calculation.You can include reference pressure effects in the force calculation in the CFX-Solver by setting the expert parameterinclude pref in forces = t.

It is also important to note that for rotating domains in a transient run, forces on wall boundaries in the CFX-Solverare evaluated in the reference frame fixed to the initial domain orientation. These quantities are not influenced byany rotation that might occur during a transient run or when a rotational offset is specified. However, results forrotating domains in a transient run may be in the rotated position (depending on the setting of Options in CFD-Post)when they are loaded into CFD-Post for post-processing.



force


>calculate force, <Location>, <Axis>, [<Phase>]

Tools > Function Calculator Examples• This calculates the total force on the default wall boundaries in the x-direction. Pressure and viscous forces are

included.

Function: force, Location: Default, Direction: Global X, Phase: All Fluids.

• This calculates the forces on inlet1 due to pressure and the advection of momentum.

Function: force, Location: inlet1, Direction: Global X, Phase: Water at RTP.

forceNormReturns the per unit width force on a line in the direction of the specified axis. It is available only for a polylinecreated by intersecting a locator on a boundary. Momentum data must also be available. The magnitude of the valuereturned can be thought of as the force in the specified direction on a polyline, if the polyline were 2D with a widthof one unit.

[<Phase>.]forceNorm[_<Axis>[_<Coord Frame>] ]()@<Location>

where:



• <Coord Frame> is available in CFD-Post only

• <Location> is any 1D location. An error will be raised if the location specified is not one-dimensional.

forceNorm_y()@Polyline1 calculates the per unit width force in the y-direction on the selected polyline.


>calculate forceNorm, <Location>, <Axis>, [<Phase>]

Tools > Function Calculator ExampleThe result from this calculation is force per unit width on Polyline1 in the x-direction.

Function: forceNorm, Location: Polyline1, Direction: Global X, Phase: All Fluids.

insideThe inside CEL function is essentially a step function variable, defined to be unity within a subdomain and zeroelsewhere. This is useful for describing different initial values or fluid properties in different regions of the domain.It is similar to the CEL subdomain variable, but allows a specific 2D or 3D location to be given. For example, 273[K] * inside()@Subdomain 1 has a value of 273 [K] at points in Subdomain 1 and 0 [K] elsewhere. Thelocation does not need to be a subdomain, but can be any 2D or 3D named sub-region of the physical location onwhich the expression is evaluated. For immersed solids simulations, the location can also be a specific immersedsolid domain, and the inside function will be updated automatically at the beginning of each time step.

inside()@<Location>

where:

• <Location> is any 2D or 3D named sub-region of the physical location on which the expression is evaluated.

• <Location> can also be an immersed solid domain on which the expression is evaluated dynamically.

35



forceNorm

NoteThe inside CEL function is not available in CFD-Post.


>calculate inside, <Location>

lengthComputes the length of the specified line as the sum of the distances between the points making up the line.

length()@<Location>

where:

• <Location> is any 1D location. Specifying a 2D location will not produce an error; the sum of the edgelengths from the elements in the locator will be returned.

length()@Polyline1 returns the length of the polyline.


>calculate length, <Location>

NoteWhile using this function in Power Syntax, the leading character is capitalized to avoid confusion withthe Perl internal command “length”.

Tools > Function Calculator ExampleThis example calculates the length of a polyline.

Function: length, Location: Polyline1.

lengthAveComputes the length-based average of the variable on the specified line. This is the 1D equivalent of the areaAvefunction. The results is independent of the nodal distribution along the line because a weighting function assigns ahigher weighting to areas of sparse nodal density.

lengthAve(<Expression>)@<Location>

where:


• <Location> is any 1D or 2D location.

lengthAve(T)@Polyline1 calculates the average temperature on Polyline1 weighted by the distancebetween each point (T is the system variable for temperature).


>calculate lengthAve, <Expression>, <Location>

Tools > Function Calculator ExampleThis calculates the average velocity on the location Polyline1 using a length-based weighting function to accountfor the distribution of points along the line.

Function: lengthAve, Location: Polyline1, Variable: Velocity.



length

lengthIntComputes the length-based integral of the variable on the specified line. This is the 1D equivalent of the areaIntfunction.

lengthInt(<Expression>)@<Location>

where:


• <Location> is any 1D location.


>calculate lengthInt, <Expression>, <Location>.

massmass()@<Location>

where:



>calculate mass, <Location>.

massAvemassAve(<var>)@<Location>

where:

• <var> is a variable



>calculate massAve, <var>, <Location>.

massFlowComputes the mass flow through the specified 2D location.

[<Phase>.]massFlow()@<Location>

where:


• <Location> is any fluid surfaces (such as Inlets, Outlets, Openings and fluid-fluid interfaces).

Air at STP.massFlow()@DegassingOutlet calculates the mass flow of Air at STP through theselected location.

For boundary locators:

• The mass flow is calculated using mass flow data from the results file, if it is available. Otherwise, an approximatemass flow is calculated.

37



lengthInt

• For multiphase cases, the mass flow through a boundary on a GGI interface evaluated in CFD-Post is anapproximation to the 'exact' mass flow evaluated by the solver. This approximation vanishes as the mesh isrefined or as the volume fraction on the interface becomes uniform.

For non-boundary locators (that is, internal locators):

• If the locator is an edge based locator (such as a cut plane or isosurface), the domain mass flow data from theresults file will be used.

• In all other cases, an approximate mass flow is calculated.

The massFlow function enables you to select the fluids to use when performing your calculation. The resultreturned is the mass flow of the selected fluids through the locator.

Mass Flow Sign ConventionThe mass flow through a surface is defined by − ⋅ρV n where V is the velocity vector and n is the surface normalvector. By convention, the surface normal at a domain boundary is directed out of the domain. Therefore, the massflow is positive at an inlet boundary with the velocity directed into the domain. For planes and surfaces that cutthrough a domain, the normal of the plane or surface is determined by from the right-hand rule and the manner inwhich the plane or surface is constructed. For example, the surface normal for a Z-X plane has the same sense anddirection as the Y-axis.

Tools > Command Editor Example>calculate massFlow, <Location>, [<Phase>]

Tools > Function Calculator ExampleThis calculates the mass flow for all fluids in the domains through the location outlet2:

Function: massFlow, Location: outlet2, Phase: All Fluids.

massFlowAveComputes the average of a variable/expression on the specified 2D location. The massFlowAve function allowsyou to select the fluids to use when performing your calculation. The result returned is the average variable value,evaluated according to the formula:

(Eq. 4.3)=ΦmassFlowAve ( ) Σ mΦΣ m( )

where Φ represents the variable/expression being averaged and m represents the local mass flow (net local massflow if more than one fluid is selected). Each summation term is evaluated on, and corresponds to, a node on the2D locator. The mass flow for each term is derived from summing contributions from the surrounding solverintegration points. As a result, the denominator evaluates to the conservative net mass flow through the 2D locator.

In cases where there is significant flow, but little or no net flow through the 2D locator (as can happen withrecirculation), the denominator of the averaging formula becomes small, and the resulting average value may becomeadversely affected. In such cases, the massFlowAveAbs (see massFlowAveAbs (p. 39)) function is a viablealternative to the massFlowAve function.

[<Phase>.]massFlowAve(<var|Expression>)@<Location>

where:


• <var|Expression> is a variable or expression

• <Location> is any fluid surfaces (such as Inlets, Outlets, Openings and fluid-fluid interfaces). An error israised if the location specified is not 2D.



Mass Flow Sign Convention

massFlowAve(Density)@Plane1 calculates the average density on Plane1 weighted by the mass flow ateach point on the location.

See the Advanced (p. 39) and Technical Note (p. 39) sections under massFlowAveAbs (p. 39) for more information.


>calculate massFlowAve, <var|Expression>, <Location>, [<Phase>]

Tools > Function Calculator ExampleThis example calculates the average velocity on Plane1 weighted by the mass flow for all fluids assigned to eachpoint on Plane1:

Function: massFlowAve, Location: Plane1, Variable: Velocity, Phase: All Fluids

massFlowAveAbsThis function is similar to the massFlowAve function (see massFlowAve (p. 38)), except that each local massflow value used in the averaging formula has the absolute function applied. That is:

(Eq. 4.4)=ΦmassFlowAveAbs ( ) Σ m ΦΣ m( )

[<Phase>.]massFlowAveAbs(<var|Expression>)@<Location>

where:




massFlowAve(Density)@Plane1 calculates the average density on Plane1 weighted by the mass flow ateach point on the location.

In cases where there is significant flow, but little or no net flow through the 2D locator (as can happen withrecirculation), the massFlowAveAbs function is a viable alternative to the massFlowAve function (seemassFlowAve (p. 38)).

AdvancedNote that the massFlowAveAbs and massFlowAve functions provide the same result, and that the denominatorevaluates to the net mass flow through the 2D locator, only when all of the flow passes through the 2D locator inthe same general direction (in other words, when there is no backflow). If there is any backflow through the 2Dlocator, the denominator in the function for massFlowAveAbs evaluates to a value of greater magnitude than theconservative net mass flow through the 2D locator (although this is not necessarily harmful to the resulting averagevalue).

The values of variables other than mass flow are stored at the mesh nodes and are applied to the locator nodes bylinear interpolation. For the mass flow variable, CFD-Post uses the integration point mass flow data if it is available;otherwise, it will approximate mass flow values based on mesh node values of velocity (and density, if available).

Technical NoteWhen integration point mass flow data is stored, backflow through the 2D locator may occur as an artifact of howthe mass flow data is applied to the locator nodes, even though there may be no actual backflow (as evidenced bya vector plot on the locator). The figure below illustrates how this may occur.

39



massFlowAveAbs

Figure 4.1. Backflow

In order to visualize this type of backflow through a locator, try making a contour plot of the variable Mass Flow,setting a user defined Range from 0 to 1 and the # of Contours to 3. This will produce a contour plot with twocolor bands: one for each general flow direction. This visualization technique works because the method of applyingintegration-point mass-flow data to locator nodes is the same for all uses of the mass flow variable involving a 2Dlocator (contour plots, massFlowAve, massFlowAveAbs, etc.).

massFlowIntIntegrates a variable over the specified 2D location. A weighting function is applied to the variable value at eachpoint based on the mass flow assigned to that point. You can also specify the fluid(s) used to calculate the massflow at each locator point.

[<Phase>.]massFlowInt(<var|Expression>)@<Location>

where:






massFlowInt


>calculate massFlowInt, <var|Expression>, <Location>, [<Phase>]

Tools > Function Calculator ExampleThis example integrates pressure over Plane1. The result is the pressure force acting on Plane1 weighted by themass flow assigned to each point on Plane1:

Function: massFlowInt, Location: Plane1, Variable: Pressure, Phase: All Fluids

massIntThe mass-weighted integration of a variable within a domain or subdomain.

massInt(<var|Expression>)@<Location>

where:


• <Location> is any 3D region (such as a domain or subdomain)


>calculate massInt, <var>, <Location>

maxValReturns the maximum value of the specified variable on the specified locator. You should create a User Variableif you want to find the maximum value of an expression.

maxVal(<var|Expression>)@<Location>

where:


• <Location> in CFX-Solver is any 2D or 3D region (such as a domain or subdomain); in CFD-Post, Pointand 1D, 2D, and 3D locators can be specified.


>calculate maxVal, <var|Expression>, <Location>

Tools > Function Calculator ExampleThis will return the maximum Yplus value on the default wall boundaries:

Function: maxVal, Location: Default, Variable: Yplus

minValReturns the minimum value of the specified variable on the specified locator. You should create a User Variable ifyou want to find the minimum value of an expression.

minVal(<var|Expression>)@<Location>

where:


• <Location> in CFX-Solver is any 2D or 3D region (such as a domain or subdomain); in CFD-Post, Pointand 1D, 2D, and 3D locators can be specified.

41



massInt


>calculate minVal, <var|Expression>, <Location>

Tools > Function Calculator ExampleThese settings will return the minimum temperature in the domain:

Function: minVal, Location: MainDomain, Variable: Temperature

probeReturns the value of the specified variable on the specified Point object.

probe(<var|Expression>)@<Location>

where:


• <Location> is any point object (such as a Source Point or Cartesian Monitor Point).

ImportantThis calculation should be performed only for point locators described by single points. Incorrect solutionswill be produced for multiple point locators.


>calculate probe, <Expression>, <Location>

Tools > Function Calculator ExampleThis example returns the density value at Point1:

Function: probe, Location: Point1, Variable: Density

rmsAveReturns the RMS average of the specified variable within a domain.

rmsAve(<var>)@<Location>

where:




>calculate rmsAve, <var>, <Location>

sumComputes the sum of the specified variable values at each point on the specified location.

sum(<var|Expression>)@<Location>

where:


• <Location> in CFX-Solver is any 3D region (such as a domain or subdomain); in CFD-Post, Point and 1D,2D, and 3D locators can be specified.



probe


>calculate sum, <var|Expression>, <Location>

Tools > Function Calculator ExampleThis example returns the sum of the finite volumes assigned to each node in the location SubDomain1. In thiscase, this sums to the volume of the subdomain:

Function: sum, Location: SubDomain1, Variable: Volume of Finite Volume

torqueReturns the torque on a 2D locator about the specified axis. The force calculated during evaluation of the torquefunction has the same behavior as the force function. For details, see force (p. 34). You can select the fluids involvedin the calculation.

[<Phase>.]torque_[<Axis>[_<Coord Frame>] ]()@<Location>

where:



• <Coord Frame>

• <Location> is any 2D region (such as a wall). If the location specified is not 2D, an error is raised.


>calculate torque, <Location>, <Axis>, [<Phase>]

Tools > Function Calculator ExampleThis example calculates the torque on Plane1 about the z-axis due to all fluids in the domain.

Function: torque, Location: Plane1, Axis: Global Z, Phase: All Fluids

volumeCalculates the volume of a 3D location.

volume()@<Location>

where:

• <Location> is any 3D region (such as a domain or subdomain). An error is raised if the location specifiedis not a 3D object. For details, see volume (p. 43).


>calculate volume, <Location>

Tools > Function Calculator ExampleThis example returns the sum of the volumes of each mesh element included in the location Volume1.

Function: volume, Location: Volume1

volumeAveCalculates the volume-weighted average of an expression on a 3D location. This is the 3D equivalent of the areaAvefunction. The volume-weighted average of a variable is the average value of the variable on a location weighted by

43



torque

the volume assigned to each point on a location. Without the volume weighting function, the average of all the nodalvariable values would be biased towards values in regions of high mesh density. The following example demonstratesuse of the function.

volumeAve(<var|Expression>)@<Location>

where:




>calculate volumeAve, <var|Expression>, <Location>

Tools > Function Calculator ExampleThis example calculates the volume-weighted average value of density in the region enclosed by the locationVolume1:

Function: volumeAve, Location: Volume1, Variable: Density

volumeIntIntegrates the specified variable over the volume location. This is the 3D equivalent of the areaInt function.

volumeInt(<var|Expression>)@<Location>

where:


• <Location> is any 3D region (such as a domain or subdomain). An error is raised if the location specifiedis not a 3D object.

For example, volumeInt(Density)@StaticMixer will calculate the total fluid mass in the domainStaticMixer.


>calculate volumeInt, <var|Expression>, <Location>

Tools > Function Calculator ExampleThis example calculates the integral of density (the total mass) in Volume1.

Function: volumeInt, Location: Volume1, Variable: Density



volumeInt

Chapter 5. Variables in ANSYS CFXThis chapter describes the variables available in ANSYS CFX:

• Hybrid and Conservative Variable Values (p. 45)

• List of Field Variables (p. 46)

• List of Particle Variables (p. 64)

• Miscellaneous Variables (p. 70)

Hybrid and Conservative Variable ValuesThe CFX-Solver calculates the solution to your CFD problem using polyhedral finite volumes surrounding thevertices of the underlying mesh elements (hexahedrons, tetrahedrons, prisms, pyramids). Analytical solutions tothe Navier-Stokes equations exist for only the simplest of flows under ideal conditions. To obtain solutions for realflows, a numerical approach must be adopted whereby the equations are replaced by algebraic approximationswhich may be solved using a numerical method.

The solution values on the boundary vertices, called conservative values, are the values obtained from solving theconservation equations for the boundary control volumes. These values are not necessarily the same as the specifiedboundary condition values, although the specified boundary value is used to close boundary fluxes for the boundarycontrol volume. For example, on a no-slip wall, the wall velocity is used to compute the viscous force for theboundary face of the boundary control volume, but the resulting control volume equation solution will not necessarilybe the wall velocity. The conservative values are representative of the boundary control volume, not the boundaryitself. For visualization purposes, it is often useful to view the specified boundary condition value for the boundaryvertices rather than the conservative values. This is especially true when the value of a conservative solution variable(such as pressure or temperature, for instance) is specified at a particular boundary condition. The specified boundaryvalues are called hybrid values. CFD-Post uses hybrid values by default for most variables. Hybrid values areobtained by overwriting the conservative results on the boundary nodes produced by the CFX-Solver with valuesbased on the specified boundary conditions. This ensures, for example, that the velocity is displayed as zero onno-slip walls. For quantitative calculations, the conservative values should normally be used because they areconsistent with the discrete solutions obtained by the solver. If you want to use these values in CFD-Post, you canselect them from the Variables Editor dialog box as described above. By default, CFD-Post uses conservativevalues when the Calculate command is used.

The difference between hybrid and conservative values at wall boundaries can be demonstrated using the followingfigure:

Using velocity as an example, the velocity value calculated at a mesh node is based upon the ‘average' in the controlvolume surrounding that node. For calculation purposes, the entire control volume is then assumed to possess thatvelocity. At a boundary node, its surrounding control volume includes an area in the bulk of the fluid (this area is

45



highlighted around the boundary node marked 1). Hence, the conservative velocity calculated at the wall node isnot zero, but an ‘average' over the control volume adjacent to the boundary. At a wall boundary node the differencebetween conservative and hybrid values can be illustrated by considering the case of the mass flow rate through thewall-adjacent control volume. If a zero velocity was enforced at the boundary node, then this would produce zeromass flow through the control volume, which is clearly not correct.

Solid-Fluid Interface Variable Values

Conservative Values at 1:1 InterfaceAt a solid-fluid 1:1 interface, duplicate nodes exist. The conservative value for the solid-side node is the variablevalues averaged over the half on the control volume that lies inside the solid. The conservative value for the fluid-sidenode is the variable values averaged over the half of the control volume that lies in the fluid.

Consider the example of heat transfer from a hot solid to a cool fluid when advection dominates within the fluid.If you create a plot across the solid-fluid interface using conservative values of temperature, then you will see asharp change in temperature across the interface. This is because values are interpolated from the interface into thebulk of the solid domain using the value for the solid-side node at the interface, while values are interpolated fromthe interface into the bulk of the fluid domain using the value for the fluid-side node at the interface. This resultsin a temperature discontinuity at the interface.

Hybrid Values at 1:1 InterfaceWhen creating plots using hybrid variable values (the default in CFD-Post), the 1:1 interface is single valued andtakes the solid-side conservative value. You can therefore expect to see the same plot within the solid, but thetemperature profile between the interface and the first node in the fluid interpolates between the solid-side interfacevalue and the first fluid node value. In this case, a discontinuity does not exist because all nodes are single valued.

Conservative values should be used for all quantitative calculations.

Conservative Values on a GGI InterfaceAt a GGI interface, the CFX Solver calculates both fluid-side and solid-side temperatures based on heat fluxconservation. These values are representative of the temperature within the half-control volumes around the verticeson the interface. The fluid-side and solid-side temperatures are generally not equal. As a result, a plot of conservativevalues of temperature will generally show a discontinuity across a GGI interface.

Hybrid Values on a GGI InterfaceAt a GGI interface, the CFX Solver calculates a "surface temperature" based on a flux-conservation equation forthe 'control surfaces' that lie between the fluid side and the solid side. The surface temperature is usually betweenthe fluid-side and solid-side temperatures. Hybrid values of temperature on a GGI interface are set equal to thesurface temperature. As a result, there is no discontinuity in hybrid values of temperature across a GGI interface.

List of Field VariablesThis section contains a list of field variables that you may have defined in CFX-Pre or that are available for viewingin CFD-Post and exporting to other files. Many variables are relevant only for specific physical models.

The information given in this section includes:

• Long Variable Name: The name that you see in the user interface.

• Short Variable Name: The name that must be used in CEL expressions.

• Units: The default units for the variable. An empty entry [ ] indicates a dimensionless variable.

NoteThe entries in the Units columns are SI but could as easily be any other system of units.

• In the Availability column:



Solid-Fluid Interface Variable Values

• A number represents the user level (1 indicates that the variable appears in default lists, 2 and 3 indicate that

the variable appears in extended lists that you see when you click ). This number is useful when using

the CFX Export facility. For details, see File Export Utility in the ANSYS CFX documentation. Note thatthe CFX-Solver may sometimes override the user-level setting depending on the physics of the problem. Inthese cases, the User Level may be different from that shown in the tables that follow.

• Boundary (B): A B in this column indicates that the variable contains only non-zero values on the boundaryof the model. See Boundary-Value-Only Variables (p. 72) for more details.

Boundary-Value-Only Variables (p. 72) in the ANSYS CFD-Post Standalone: User's Guide describes theuseful things that you can do with variables that are defined only on the boundaries of the model.

• A indicates the variable is available for mesh adaption

• C indicates the variable is available in CEL

• DT indicates the variable is available for data transfer to ANSYS

• M indicates the variable is available for monitoring

• P indicates the variable is available for particle user-routine argument lists

• PR indicates the variable is available for particle results

• R indicates the variable is available to be output to the results, transient results, and backup files

• RA indicates the variable is available for radiation results

• TS indicates the variable is available for transient statistics

• Definition: Defines the variable.

This is not a complete list of variables. Information on obtaining details on all variables is available. For details,see RULES and VARIABLES Files in the ANSYS CFX documentation.

NoteVariables with names shown in bold text are not output to CFD-Post. However, some of these variablescan be output to CFD-Post by selecting them from the Extra Output Variables List on the Results tabof the Solver > Output Control details view of CFX-Pre.

Common Variables Relevant for Most CFD CalculationsThe following table contains a list of variables (with both long and short variable names) that can be used whenworking with CFD calculations. For an explanation of the column headings, see List of Field Variables (p. 46).

DefinitionAvailabilityUnitsShortVariableName

Long VariableName

For Fixed and Variable Composition Mixture, thedensity is determined by a mass fraction weightedharmonic average:

+ + … + =Yρ

Yρ

Yρ ρ

1N

N

A

A

B

B mix

1

A, C, M,P, R, TS

[kgm^-3]

densityDensity

Dynamic viscosity (μ), also called absolute viscosity, isa measure of the resistance of a fluid to shearing forces,

2

A, C, M,P, R, TS

[kg m -1 s -1]viscosityDynamic Viscosity

and appears in the momentum equations. Using anexpression to set the dynamic viscosity is possible. Fordetails, see Non-Newtonian Flow in the CFXdocumentation.

Velocity vector.1[m s^-1]velVelocitya

47



Common Variables Relevant for Most CFD Calculations


Long VariableName

A, C, M,P, R, TS

Components of velocity.1[m s^-1]uVelocity u

A, C, M,P, R, TS

v

w

Velocity v

Velocity w

Both Pressure and Total Pressure are measuredrelative to the reference pressure that you specified on the

1

A, C, M,P, R, TS

[kg m -1 s -2]pPressure

Domains panel in CFX-Pre. Additionally, Pressure isthe total normal stress, which means that when using thek-e turbulence model, Pressure is the thermodynamicpressure plus the turbulent normal stress. StaticPressure is the thermodynamic pressure, in most casesthis is the same as Pressure.

CFX solves for the relative Static Pressure(thermodynamic pressure) pstat in the flow field, and is

related to Absolute Pressure = +p p pabs stat ref.

3[kg m -1 s -2]pstatStatic Pressure

The total pressure, ptot, is defined as the pressure that

would exist at a point if the fluid was brought

2

A, C, M,P, R, TS

[kg m -1 s -2]ptotTotal Pressure

instantaneously to rest such that the dynamic energy ofthe flow converted to pressure without losses. Thefollowing three sections describe how total pressure iscomputed for a pure component material with constantdensity, ideal gas equation of state and a general equationof state (CEL expression or RGP table). For details, seeScalable Wall Functions in the ANSYS CFXdocumentation.

For details, see Scalable Wall Functions in the ANSYSCFX documentation.

3,BPawall shearWall Shear

Volume of finite volume. For details, see Discretizationof the Governing Equations in the ANSYS CFXdocumentation.

3

C, DT, R,TS

Volume of FiniteVolume

Cartesian coordinate components.2[m]xX coordinate

C

2[m]yY coordinate

C

2[m]zZ coordinate

C

Kinematic diffusivity describes how rapidly a scalarquantity would move through the fluid in the absence of

2

C, M, P, R,TS

visckinKinematicDiffusivity

convection. For convection-dominated flows, thekinematic diffusivity can have little effect becauseconvection processes dominate over diffusion processes.



Common Variables Relevant for Most CFD Calculations


Long VariableName

For details see Non-Newtonian Flow in the ANSYS CFXdocumentation.

2

A, C, M,R, TS

[s^-1]sstrnrShear Strain Rate

For details, see Specific Heat Capacity in the ANSYSCFX documentation.

2

A, C, M,R, TS

[m^2s^-2K^-1]

CpSpecific HeatCapacity atConstant Pressure

2[m^2s^-2K^-1]

CvSpecific HeatCapacity atConstant Volume

A, C, M,P, R, TS

Thermal conductivity, λ, is the property of a fluid thatcharacterizes its ability to transfer heat by conduction.

2

A, C, M,R, TS

[kg ms^-3K^-1]

condThermalConductivity

For details, see Thermal Conductivity in the ANSYS CFXdocumentation.

The static temperature, Tstat, is the thermodynamictemperature, and depends on the internal energy of the

1

A, C, DT,M, P, R,TS

[K]TTemperature

fluid. In CFX, depending on the heat transfer model youselect, the flow solver calculates either total or staticenthalpy (corresponding to the total or thermal energyequations).

The total temperature is derived from the concept of totalenthalpy and is computed exactly the same way as static

1

A, C, M,P, R, TS

[K]TtotTotal Temperature

temperature, except that total enthalpy is used in theproperty relationships.

A heat flux is specified across the wall boundary. Apositive value indicates heat flux into the domain. For

2,B

C, DT, R,TS

[W m^-2]QwallWall Heat Flux

multiphase cases, when the bulk heat flux into both phasesis set, this option is labeled Wall Heat Flux instead of HeatFlux. When set on a per fluid basis, this option is labelledHeat Flux.

For details, see Wall Heat Transfer in the ANSYS CFXdocumentation.

2,B

C, R, TS

[W m^-2K^-1]

htcWall Heat TransferCoefficient

h totFor details, see Transport Equations in the ANSYS CFXdocumentation.

A, C, M,R, TS

[m^2s^-2]

htotTotal Enthalpy

For details, see Static Enthalpy in the ANSYS CFXdocumentation.

2

A, C, M,P, R, TS

[m^2s^-2]

enthalpyStatic Enthalpy

aWhen a rotating frame of reference is used, all variables in the CFX-5 results file are relative to the rotating frame, unless specified as a StnFrame variable.

Variables Relevant for Turbulent FlowsThe following table contains a list of variables (with both long and short variable names) that can be used whenworking with turbulent flows. For an explanation of the column headings, see List of Field Variables (p. 46).

49



Variables Relevant for Turbulent Flows

A B in the Type column indicates that the variable contains only non-zero values on the boundary of the model.


Long VariableName

Controls blending between RANS and LES regimes forthe DES model

2

C, M, R, TS

[ ]desbfBlendingFunction for DESmodel

For details, see The k-epsilon Model in CFX in theANSYS CFX documentation.

1

A, C, M, P,R, TS

[m^2s^-2]

keTurbulenceKinetic Energy

The rate at which the velocity fluctuations dissipate. Fordetails, see The k-epsilon Model in CFX in the ANSYSCFX documentation.

1

A, C, M, P,R, TS

[m^2s^-3]

edTurbulence EddyDissipation

1[s^-1]tefTurbulent EddyFrequency A, C, M, P,

R, TS

The “eddy viscosity model” proposes that turbulenceconsists of small eddies that are continuously forming

2

A, C, M, P,R, TS

[kg m^-1s-1]

eddy viscosityEddy Viscosity

and dissipating, and in which the Reynolds stresses areassumed to be proportional to mean velocity gradients.For details, see Eddy Viscosity Turbulence Models in theANSYS CFX documentation.

This is a tensor quantity with six components. For details,see Statistical Reynolds Stresses and Reynolds StressTurbulence Models in the ANSYS CFX documentation.

2

A, C, M, P,R, TS

[m^2s^-2]

rsReynolds Stress

In LES runs, Reynolds Stress components areautomatically generated using running statistics of the

3

M, R

[m^2s^-2]

rsstat uuStatisticalReynolds Stressuu instantaneous, transient velocity field. For details, see

Statistical Reynolds Stresses in the ANSYS CFXdocumentation.3

M, R

[m^2s^-2]

rsstat vvStatisticalReynolds Stressvv

3[m^2s^-2]

rsstat wwStatisticalReynolds Stressww

M, R

3[m^2s^-2]

rsstat uvStatisticalReynolds Stressuv

M, R

3[m^2s^-2]

rsstat uwStatisticalReynolds Stressuw

M, R

3[m^2s^-2]

rsstat vwStatisticalReynolds Stressvw

M, R

For details, see Statistical Reynolds Stresses in theANSYS CFX documentation.

3

C, M, R

[m^2s^-2]

uuVelocityCorrelation uu



Variables Relevant for Turbulent Flows


Long VariableName

3[m^2s^-2]

vvVelocityCorrelation vv C, M, R

3[m^2s^-2]

wwVelocityCorrelation ww C, M, R

3[m^2s^-2]

uvVelocityCorrelation uv C, M, R

3[m^2s^-2]

uwVelocityCorrelation uw C, M, R

3[m^2s^-2]

vwVelocityCorrelation vw C, M, R

A variable based on the distance from the wall to the firstnode and the wall shear stress. For details, see SolverYplus and Yplus in the ANSYS CFX documentation.

2,B

C, R, TS

[ ]yplusstdYplus

A deprecated internal variable. For details, see SolverYplus and Yplus in the ANSYS CFX documentation.

2,B

C, R, TS

[ ]yplusSolver Yplus

Variables Relevant for Buoyant FlowThe following table contains a list of variables (with both long and short variable names) that can be used whenworking with buoyant flows. For an explanation of the column headings, see List of Field Variables (p. 46).


Long VariableName

For details, see Basic Capabilities Modeling >Physical Models > Buoyancy in the ANSYS CFXSolver Modeling Guide.

2

C

[K^ -1]betaThermalExpansivity

Variables Relevant for Compressible FlowThe following table contains a list of variables (with both long and short variable names) that can be used whenworking with compressible flows.


Long VariableName

− ∂∂ρρT

p

12

C, M, R

[K^-1] compisoPIsobaricCompressibility

∂∂ρρpT

12

C, M, R

[m s^2kg^-1 ]

compisoTIsothermalCompressibility

51



Variables Relevant for Buoyant Flow


Long VariableName

For details, see List of Symbols in the CFXdocumentation.

1

A, C, M, R, TS

[ ]MachMach Number

The variable takes a value of 0 away from a shockand a value of 1 in the vicinity of a shock.

2

A, C, M, R, TS

[ ]shockindicator

Shock Indicator

⎛⎝⎜

⎞⎠⎟

⎛⎝⎜

⎞⎠⎟

∂∂ρρps

12

C, M, R

[m s^2kg^-1]

compisoSIsentropicCompressibility

Variables Relevant for Particle TrackingThe following table contains a list of variables (with both long and short variable names) that can be used whenworking with compressible flows.

DefinitionUser LevelUnitsShortVariableName

Long VariableName

User-specified latent heat for phase pairs involving a particlephase.

2

C, R, M

[ ]lheatLatent Heat

Momentum source from particle phase to continuous phase.2[ ]ptmomsrcParticleMomentumSource

A, C, M, P,R

Diameter of a particle phase.3[ ]particlediameter

Particle Diameter

A, C, M, R

Variables Relevant for Calculations with a Rotating Frame ofReference

The following table contains a list of variables (with both long and short variable names) that can be used whenworking with a rotating frame of reference. For an explanation of the column headings, see List of FieldVariables (p. 46).


Long VariableName

The velocity in the rotating frame of reference isdefined as:

2

A, C, M, P,R, TS

[kg m^-1 s^-2]ptotstnTotal Pressure inStn Frame

= − ×U U ω Rrel stn2[K]TtotstnTotal

Temperature inStn Frame

where ω is the angular velocity, R is the local radiusvector, and Ustn is velocity in the stationary frameof reference.

A, C, DT,M, P, R, TS

2[kg m^2 s^-2]htotstnTotal Enthalpy inStn Frame For details, see Rotating Frame Quantities in the

CFX documentation.A, C, M, R,TS



Variables Relevant for Particle Tracking


Long VariableName

1[ ]MachstnMach Number inStn Frame A, C, M, R,

TS

1[m s^-1]velstnVelocity in StnFrame A, C, M, R,

TS

Variables Relevant for Parallel CalculationsThe following table contains a list of variables (with both long and short variable names) that can be used whenworking with parallel calculations. For an explanation of the column headings, see List of Field Variables (p. 46).


Long VariableName

The partition that the node was in for the parallel run.2[ ]Real PartitionNumber C, M, R

Variables Relevant for Multicomponent CalculationsThe following table contains a list of variables (with both long and short variable names) that can be used whenworking with multicomponent calculations. For an explanation of the column headings, see List of FieldVariables (p. 46).


Long VariableName

The fraction of a component in a multicomponent fluidby mass.

1

A, C, M, P,R, TS

[ ]mfMass Fraction

The concentration of a component.2[kg m^-3]mconcMassConcentration A, C, M, P,

R, TS

Variables Relevant for Multiphase CalculationsThe following table contains a list of variables (with both long and short variable names) that can be used whenworking with multiphase calculations. For an explanation of the column headings, see List of Field Variables (p. 46).


Long VariableName

Interface area per unit volume for Eulerian multiphasefluid pairs.

3

C

[m^-1]area densityInterfacial AreaDensity

Interface mass transfer rate for Eulerian multiphase fluidpairs.

3

C

[ ]ipmt rateInterphase MassTransfer Rate

53



Variables Relevant for Parallel Calculations


Long VariableName

For details, see Volume Fraction in the ANSYS CFXdocumentation.

1

A, C, M, P,R, TS

[ ]vfVolume Fraction

For details, see Volume Fraction in the ANSYS CFXdocumentation.

2

A, C, M, R,TS

[ ]vfcConservativeVolume Fraction

Velocity of an algebraic slip component relative to themixture.

2

C, M, R, TS

[ ]drift velocityDrift Velocity

Reynolds number for Eulerian multiphase fluid pairs.3[ ]slip ReSlip ReynoldsNumber C

Velocity of an algebraic slip component relative to thecontinuous component.

1

C, M, R, TS

[ ]slipvelSlip Velocity

Surface tension coefficient between fluids in a fluid pair.2[N m^-1]surface tensioncoefficient

Surface TensionCoefficient C

Similar to area density, but values are not clipped to benon-zero.

3

C

[m^-1]unclipped areadensity

UnclippedInterfacial AreaDensity

The Fluid.Volume Fraction multiplied by theFluid.Velocity.

1

A, C, M, R,TS

[m s^-1]volflxSuperficialVelocity

Variables Relevant for Radiation CalculationsThe following table contains a list of variables (with both long and short variable names) that can be used whenworking with radiation calculations. For an explanation of the column headings, see List of Field Variables (p. 46).

A B in the Type column indicates that the variable contains only non-zero values on the boundary of the model.


Long VariableName

Wall Radiative Heat Flux represents the net radiativeenergy flux leaving the boundary. It is computed as the

2,B

DT, R, TS

[W m^-2]QradWall RadiativeHeat Flux

difference between the radiative emission and theincoming radiative flux (Wall Irradiation Flux).

Wall Heat Flux is sum of the Wall Radiative Heat Fluxand the Wall Convective Heat Flux. For an adiabaticwall, the sum should be zero.

2,B

C, DT, R,TS

[W m^-2]QwallWall Heat Flux

Wall Irradiation Flux represents the incoming radiativeflux. It is computed as the solid angle integral of the

2,B

C, DT, R,TS

[W m^-2]irradWall IrradiationFlux

incoming Radiative Intensity over a hemisphere on theboundary. For simulations using the multiband model,the Wall Irradiation Flux for each spectral band is alsoavailable for post-processing.



Variables Relevant for Radiation Calculations

Variables for Total Enthalpies,Temperatures, and PressuresThe following table lists the names of the various total enthalpies, temperatures, and pressures when visualizingresults in CFD-Post or for use in CEL expressions. For an explanation of the column headings, see List of FieldVariables (p. 46).

DefinitionAvailabilityUnitsShort VariableName

Long Variable Name

h totFor details, see Transport Equations inthe ANSYS CFX documentation.

A, C, M, R, TS[m^2 s^-2]htotTotal Enthalpy

IA, C, M, R, TS[m^2 s^-2]rothalpyRothalpy

h tot,stnA, C, M, R, TS[m^2 s^-2]htotstnTotal Enthalpy in Stn

Frame

Ttot,relA, C, DT, M,P, R, TS

[K]TtotrelTotal Temperature inRel Frame

TtotA, C, DT, M,P, R, TS

[K]TtotTotal Temperature

Ttot,stnA, C, DT, M,P, R, TS

[K]TtotstnTotal Temperature inStn Frame

Ptot,relA, C, M, P, R,TS

[kg m -1 s -2]ptotrelTotal Pressure in RelFrame

PtotA, C, M, P, R,TS

[kg m -1 s -2]ptotTotal Pressure

Ptot,stnA, C, M, P, R,TS

[kg m -1 s -2]ptotstnTotal Pressure in StnFrame

Variables and Predefined Expressions Available in CELExpressions

The following is a table of the more common variables and predefined expressions that are available for use withCEL when defining expressions. To view a complete list, open the Expressions workspace. For an explanation ofthe column headings, see List of Field Variables (p. 46).

Many variables and expressions have a long and a short form (for example, Pressure or p).

Additional Variables and expressions are available in CFD-Post. For details, see CFX Expression Language (CEL)in CFD-Post (p. 259).

55



Variables for Total Enthalpies, Temperatures, and Pressures

Table 5.1. Common CEL Single-Value Variables and Predefined Expressions


Long VariableName

These single-value variables enable access totimestep, timestep interval, and iterationnumber in CEL expressions. They may beuseful in setting parameters such as thePhysical Timescale via CEL expressions. Fordetails, see Timestep, Timestep Interval, andIteration Number Variables (p. 62).

2

C

[ ]acplgstepAccumulatedCoupling Step

2

C

[ ]aiternAccumulatedIteration Number

2

C

[ ]atstepAccumulatedTime Step

2

C

[ ]citernCurrent IterationNumber

2

C

[ ]cstaggerCurrent StaggerIteration

2

C

[ ]ctstepCurrent TimeStep

2

C

[ ]sstepSequence Step

2

C

[s]dtstepTime Step Size

2

C

[s]tTime

NoteVariables with names shown in bold text in the tables that follow are not output to CFD-Post. However,some of these variables can be output to CFD-Post by selecting them from the Extra Output VariablesList on the Results tab of the Solver > Output Control details view in CFX-Pre.



Variables and Predefined Expressions Available in CEL Expressions

Table 5.2. Common CEL Field Variables and Predefined Expressions


Long VariableName

Axial spatial location measured along thelocally-defined axis from the origin of the

2

C

[m]aaxisAxial Distance

latter. When the locally-defined axis happensto be the z-axis, z and aaxis are identical.

1[m^-1]absorpAbsorptionCoefficient C, M, R, TS

2[m]bnd distanceBoundaryDistance A, C, M, R, TS

3[m^-2]bnd scaleBoundary Scale

C, M, R, TS

3[ ]afContact AreaFraction M

Additional Variable name[AV name][AV name]

2[K^-1]betaThermalExpansivity C

3[kg m^-3]deneffEffectiveDensity A, C, M, R, TS

2[kg m^-3]densityDensity

A, C, M, P, R,TS

1[m^2 s^-3]edTurbulence EddyDissipation A, C, M, P, R,

TS

1[kg m^-1 s^-1]eddy viscosityEddy Viscosity

A, C, M, P, R,TS

1[ ]emisEmissivity

C

1[m^-1]extinctExtinctionCoefficient C

1[m^2 s^-2]keTurbulenceKinetic Energy A, C, M, P, R,

TS

1[ ]MachMach Number

A, C, M, R, TS

Mach Number in Stationary Frame1[ ]MachstnMach Number inStn Frame A, C, M, R, TS

57





Long VariableName

Mass concentration of a component2

A, C, M, P, R,TS

[m^-3 kg]mconcMassConcentration

1

A, C, M, P, R,TS

[ ]mfMass Fraction

2

A, C, M, R, TS

[ ]mfcConservativeMass Fraction

3

C, P

[m]mean particlediameter

Mean ParticleDiameter

The displacement relative to the previousmesh

3

C, M, R, TS

[m]meshdispMeshDisplacement

Ratio of largest to smallest sector volumesfor each control volume.

2

C, M, R, TS

[ ]mesh exp factMesh ExpansionFactor

Simulation time at which the mesh was lastre-initialised (most often due to interpolationthat occurs as part of remeshing)

2

C

[s]meshinittimeMeshInitialisationTime

Mixture Fraction Mean1

A, C, M, R, TS

[ ]mixfrcMixture Fraction

3

M

[m]mixture lengthscale

Mixture ModelLength Scale

1

A, C, M, R, TS

[ ]mixvarMixture FractionVariance

2

A, C, M, P, R,TS

[m^-3 mol]molconcMolarConcentration

2

A, C, M, P, R,TS

[ ]molfMolar Fraction

3

C, P

[kg mol^-1]mwMolar Mass

A measure of the average mesh orthogonalityangle

2

C, M, R, TS

[rad]orthangleOrthogonalityAngle

A measure of the worst mesh orthogonalityangle

2

C, M, R, TS

[rad]orthangleminOrthogonalityAngle Minimum

A non-dimensional measure of the averagemesh orthogonality

2

C, M, R, TS

orthfactOrthogonalityFactor





Long VariableName

A measure of the worst mesh orthogonalityangle

2

C, M, R, TS

orthfactminOrthogonalityFactor Minimum

1

A, C, M, P, R,TS

[kg m^-1 s^-2]pPressure

2

A, C, M, R, TS

[kg m^-1 s^-2]pabsAbsolutePressure

The Reference Pressure is the absolutepressure datum from which all other pressurevalues are taken. All relative pressurespecifications in CFX are relative to theReference Pressure. For details, seeSetting a Reference Pressure in the ANSYSCFX documentation.

2

C

[kg m^-1 s^-2]prefReferencePressure

Radial spatial location. = +r x y2 2. For

details, see CEL Variables r and theta (p. 61).

2

C

[m]rDistance fromlocal z axis

Radial spatial location measured normal tothe locally-defined axis. When thelocally-defined axis happens to be the z-axis,r and raxis are identical.

2

C

[m]raxisRadius

1

RA

[kg s^-3]rademisRadiativeEmission

1

C, DT, M, R,TS

[kg s^-3]radincIncidentRadiation

Radiative Emission. This is written to theresults file for Monte Carlo simulations asRadiation Intensity.NormalizedStd Deviation.

1

A, C, M, P, R,TS

[kg s^-3]radintRadiationIntensity

1

C, R, TS

[ ]refracRefractive Index

Non-dimensional radius (only available whena rotating domain exists). For details, see CELVariable rNoDim (p. 62).

2

C

[ ]rNoDimNondimensionalradius

The six Reynolds Stress components2

A, C, M, P, R,TS

[m^2 s^-2]rs uu, rs vv,rs ww, rs uv,rs uw, rs vw

Reynolds Stress

The six Statistical Reynolds Stresscomponents

3

M, R

[m^2 s^-2]rsstat uu,rsstat vv,rsstat ww,rsstat uv,rsstat uw,rsstat vw

StatisticalReynolds Stress

59





Long VariableName

1

C, M, R, TS

[m^-1]scatterScatteringCoefficient

1

A, C, M, R, TS

[ ]sootmfSoot MassFraction

1

A, C, M, R, TS

[m^-3]sootnclSoot NucleiSpecificConcentration

3

A, C, M, R, TS

[m^3 kg^-1]specvolSpecific Volume

2

C, M, R, TS

[m s^-1]speedofsoundLocal Speed ofSound

Subdomain variable (1.0 in subdomain, 0.0elsewhere). For details, see CEL Variable"subdomain" and CEL Function"inside" (p. 62).

2

C

[ ]subdomainSubdomain

inside variable (1.0 in subdomain, 0.0elsewhere). For details, see CEL Variable"subdomain" and CEL Function"inside" (p. 62).

inside()@<Locations>

inside()@<Locations>

taxis is the angular spatial location measuredaround the locally-defined axis, when thelatter is defined by the Coordinate Axisoption. When the locally defined axis is thez(/x/y)-axis, taxis is measured from thex(/y/z)-axis, positive direction as perright-hand rule.

2

C

[rad]taxisTheta

1

A, C, M, P, R,TS

[s^-1]tefTurbulence EddyFrequency

Angle, arctan(y/x). For details, see CELVariables r and theta (p. 61).

2

C

[rad]thetaAngle aroundlocal z axis

The total displacement relative to the initialmesh

1

C, DT, M, R,TS

[m]meshdisptotTotal MeshDisplacement

Velocity in the x, y, and z coordinatedirections

1

A, C, M, P, R,TS

[m s^-1]u

v

w

Velocity u

Velocity v

Velocity w

Velocity in Stationary Frame in the x, y, andz coordinate directions

1

A, C, M, R, TS

[m s^-1]velstn u

velstn v

velstn w

Velocity in StnFrame u

Velocity in StnFrame v

Velocity in StnFrame w





Long VariableName

1

A, C, M, P, R,TS

[ ]vfVolume Fraction

The variable <fluid>.ConservativeVolume Fraction should not usually beused for post-processing.

2

A, C, M, R, TS

[ ]vfcConservativeVolume Fraction

2

A, C, M, P, R,TS

[m^2 s^-1]visckinKinematicViscosity

2

A, C, M, P, R,TS

[m]wall distanceWall Distance

3

M, R, TS

[m^2]wall scaleWall Scale

System Variable PrefixesIn order to distinguish system variables of the different components and fluids in your CFX model, prefixes areused. For example, if carbon dioxide is a material used in the fluid air, then some of the system variables that youmight expect to see are:

• air.density - the density of air

• air.viscosity - the viscosity of air

• air.carbondioxide.mf - the mass fraction of carbon dioxide in air.

In a single phase simulation the fluid prefix may be omitted. For multiphase cases a fluid prefix indicates a specificfluid; omitting the prefix indicates a bulk or fluid independent variable, such as pressure.

CEL Variables r and thetar is defined as the normal distance from the third axis with respect to the reference coordinate frame. theta isdefined as the angular rotation about the third axis with respect to the reference coordinate frame.

The variables Radius and theta are available only when the rotational axis has been defined. The rotational axiscan either be defined in the results file or in CFD-Post through the Initialization panel in the Turbo workspace.

Notetheta is expressed in radians and will have values between −π and π.

r and theta are particularly useful for describing radial distributions, for instance the velocity profile at the inletto a pipe.

61




Figure 5.1. r and theta with Respect to the Reference Coordinate Frame

CEL Variable rNoDimrNoDim is a dimensionless system variable that can be useful for rotating machinery applications. It is a ratio ofradii, defined to be zero at the minimum radius and unity at the maximum radius, so that in general:

= −−

rNoDim R RR R

min

max min

where R is the radius of any point in the domain from the axis of rotation. rNoDim is only available for domainsdefined with a rotating frame of reference.

CEL Variable "subdomain" and CEL Function "inside"subdomain is essentially a step function variable, defined to be unity within a subdomain and zero elsewhere.This is useful for describing different initial values or fluid properties in different regions of the domain. It worksin all subdomains but cannot be applied to specific subdomains (for example, an expression for temperature in asubdomain could be 373*subdomain [K]).

The inside CEL function can be used in a similar way to the subdomain variable, but allows a specific 2D or3D location to be given. For example, 273 [K] * inside()@Subdomain 1 has a value of 273 [K] at pointsin Subdomain 1 and 0 [K] elsewhere. Furthermore, the location can be any 2D or 3D named sub-region of thephysical location on which the expression is evaluated. The location can also be an immersed solid domain.

Timestep,Timestep Interval, and Iteration Number VariablesThese variables allow access to timestep, timestep interval, and iteration number in CEL expressions. They may beuseful in setting parameters such as the Physical Timescale via CEL expressions.

In CFD-Post, sstep is the 'global' sequence time step. It is equivalent to the Step value in the Timestep Selector(p. 201) in ANSYS CFD-Post Standalone: User's Guide.

Steady-State RunsIn steady-state runs, only aitern (or, equivalently atstep) and citern (or, equivalently ctstep) are of use.citern gives the outer iteration number of the current run. The outer iteration number begins at 1 for each run,irrespective of whether it is a restarted run. aitern gives the accumulated outer iteration number, which accumulatesacross a restarted run.

Transient RunsIn transient runs, atstep and ctstep are used for the accumulated and current timestep numbers of the outertimestep loop. citern gives the current coefficient loop number within the current timestep. Thus, citern willcycle between 1 and n for each timestep during a transient run, where n is the number of coefficient loops. aiternis equivalent to citern for transient runs.




ANSYS Multi-field RunsFor ANSYS Multi-field runs, cstagger and acplgstep are also available. cstagger gives the current staggeriteration, which will cycle between 1 and n for each coupling step of the run. acplgstep gives the accumulatedcoupling step. This gives the multi-field timestep number or "coupling step" number for the run, and accumulatesacross a restarted run. For transient ANSYS Multi-field runs where the CFX timestep is the same as the multi-fieldtimestep, acplgstep is equivalent to atstep.

Expression NamesYour CEL expression name can be any name that does not conflict with the name of a CFX system variable,mathematical function, or an existing CEL expression. The RULES and VARIABLES files provide information onvalid options, variables, and dependencies. Both files are located in <CFXROOT>/etc/ and can be viewed in anytext editor.

Scalar ExpressionsA scalar expression is a real valued expression using predefined variables, user variables, and literal constants (forexample, 1.0). Note that literal constants have to be of the same dimension. Scalar expressions can include theoperators + - * / and ^ and several of the mathematical functions found in standard Fortran (for example, sin() andexp()).

An expression's value is a real value and has specified dimensions (except where it is dimensionless - but this isalso a valid dimension setting).

For example, if t is time and L is a length then the result of L/t has the same dimensions as speed.

The + and - operators are only valid between expressions with the same dimensions and result in an expression ofthose dimensions.

The * and / operators combine the dimensions of their operands in the usual fashion. X^I, where I is an integer,results in an expression whose dimensions are those of X to the power I. The trigonometric functions all work interms of an angle in radians and a dimensionless ratio.

Expression PropertiesThere are three properties of expressions:

• An expression is a simple expression if the only operations are +, -, *, / and there are no functions used in theexpression.

• An expression is a constant expression if all the numbers in the expression are explicit (that is, they do notdepend on values from the solver).

• An expression is an integer expression if all the numbers in the expression are integers and the result of eachfunction or operation is an integer.

For example (3+5)/2 is a simple, constant, integer expression. However, 2*(1/2) is not a constant integer expression,since the result of 1/2 is 0.5, not an integer. Also 3.*4 is not a constant integer expression, since 3. is not an integer.Moreover 2^3 is not a simple, constant, integer expression, since ^ is not in the list (+, -, *, /).

Expressions are evaluated at runtime and in single precision floating point arithmetic.

Available and Unavailable VariablesCFX System Variables and user-defined expressions will be available or unavailable depending on the simulationyou are performing and the expressions you want to create. In some circumstances, System Variables are logicallyunavailable; for instance, time (t) is not available for steady-state simulations. In others, the availability of a SystemVariable is not allowed for physical model reasons. For example, density can be a function of pressure (p), temperature(T) and location (x, y, z), but no other system variables.

Information on how to find dependencies for all parameters is available in the RULES and VARIABLES files. Bothfiles are located in <CFXROOT>/etc/ and can be viewed in any text editor.

The expression definition can depend on any system variable. If, however, that expression depends on a systemvariable that is unavailable for a particular context, then that expression will also be unavailable.

63




List of Particle VariablesThis section describes the following types of particle variables that you may have defined in CFX-Pre or that areavailable for viewing in CFD-Post and exporting to other files. Many variables are relevant only for specific physicalmodels.

• Particle Track Variables (p. 64)

• Particle Field Variables (p. 65)

• Particle Boundary Vertex Variables (p. 68)

Some variables are defined only on the boundaries of the model. When using these variables in CFD-Post, thereare a limited number of useful things that you can do with these. For details, see Boundary-Value-Only Variables(p. 72) in the ANSYS CFD-Post Standalone: User's Guide.

The following information is given for particle variables described in this section:

• Long Variable Name: The name that you see in the user interface.

• Short Variable Name: The name that must be used in CEL expressions.

• Units: The default units for the variable. An empty entry [ ] indicates a dimensionless variable.

NoteThe entries in the Units columns are SI but could as easily be any other system of units.

• Type (User Level, Boundary)

User Level: This number is useful when using the CFX Export facility. For details, see File Export Utility inthe ANSYS CFX documentation. Note that the CFX-Solver may sometimes override the user-level settingdepending on the physics of the problem. In these cases, the User Level may be different from that shown inthe table below.

Boundary (B): A B in this column indicates that the variable contains only non-zero values on the boundaryof the model. See Boundary-Value-Only Variables (p. 72) for more details.

This section does not cover the complete list of variables. For information on obtaining details on all variables, seeRULES and VARIABLES Files in the ANSYS CFX documentation.

NoteVariables with names shown in bold text are not output to CFD-Post. However, some of these variablescan be output to CFD-Post by selecting them from the Extra Output Variables List on the Results tabof the Solver > Output Control details view of CFX-Pre.

Particle Track VariablesParticle track variables are particle variables that are defined directly on each track. These variables are defined onthe particle positions for which track information is written to the results file. Direct access to the particle trackvariables outside of CFD-Post is only possible if the raw track file is kept after a particle run.

Particle track variables can only be used in two ways: to color particle tracks in CFD-Post, and to be used as inputto Particle User Fortran. Particle track variables can be exported from CFD-Post along the particle tracks.

NoteParticle track variables are not available for use in CEL expressions and general User Fortran, and theyalso cannot be monitored during a simulation.

For Particle User Fortran, additional track variables can be specified in the argument list for the user routine, whichare not available in CFD-Post:

AvailabilityUnitsShort Variable NameLong Variable Name

2[ ]pteoParticle Eotvos Number



List of Particle Variables


PR

2[ ]ptmoParticle Morton Number

PR

2[ ]ptnuParticle Nusselt Number

PR

2[ ]ptonParticle Ohnesorge Number

PR

2[ ]ptreParticle Reynolds Number

PR

2[ ]ptweParticle Weber Number a

PR

2[m s^-1]ptslipvelParticle Slip Velocity

PR

2[m]ptposParticle Position

PR

3[radian]particle impact angleParticle Impact Angle b

PR

aNote: Weber number is based on particle density and particle slip velocity.bNote: The impact angle is measured from the wall.

Particle Field VariablesParticle field variables are particle variables that are defined at the vertices of the fluid calculation. In contrast totrack variables, these variables can be used in the same way as “standard” Eulerian variables. This means that particlefield variables are available for use in CEL expressions and User Fortran, they can be monitored during a simulation,and are available for general post-processing in CFD-Post. Additionally, particle field variables can be used in thesame way as particle track variables as input to particle User Fortran and for coloring tracks. When used for coloringtracks, the field variables have to be interpolated onto the tracks, and so this operation will be slower than coloringwith a track variable.

The following particle variables are available as field variables:

Particle Sources into the Coupled Fluid PhaseFor fully-coupled particle simulations involving energy, momentum and mass transfer to the fluid phase, the followingvariables are written to the results file:


2[W m^-3]ptenysrcParticle Energy Source

A, C, M, P, R

2[W m^-3 K^-1]ptenysrccParticle Energy Source Coefficient

A, C, M, P, R

2[kg m^-2 s^-2]ptmomsrcParticle Momentum Source

A, C, M, P, R

2[kg m^-3 s^-1]ptmomsrccParticle Momentum Source Coefficient

65



Particle Field Variables


A, C, M, P, R

2[kg s^-1 m^-3]ptmassrctotTotal Particle Mass Source

A, C, M, P, R

2[kg s^-1 m^-3]ptmassrcctotTotal Particle Mass Source Coefficient

A, C, M, P, R

For multi-component mass transfer, the following Additional Variables are available a:

2[kg s^-1 m^-3]ptmassrcParticle Mass Source

A, C, M, P, R

2[kg s^-1 m^-3]ptmassrccParticle Mass Source Coefficient

A, C, M, P, R

aThe variables for multi-component take the following form: <Particle Type>.<Particle Component>.<Variable Name>

Particle source terms are accumulated along the path of a particle through a control volume and stored at thecorresponding vertex. A smoothing procedure can be applied to the particle source terms, which may help withconvergence or grid independence. For details, see Particle Source Smoothing in the CFX documentation.

Particle Radiation Variables


2[W m^-3]ptremissParticle Radiative Emission

A, C, M, P, R

2[m^-1]ptabscoefParticle Absorption Coefficient

A, C, M, P, R

Particles can also interact with the radiation field and either emit or absorb radiation.

Particle Vertex VariablesBy default, particle vertex variables are not written to the results file, except for the Averaged VolumeFraction. The other vertex variables can be written to the results file if they are selected from the Extra OutputVariables List in the Output Control section of CFX-Pre or if they are used in a monitor point, CEL expressionor in (Particle) User Fortran.

The following particle variables are available:


1[m s^-1]averaged velAveraged Velocity

A, C, M, P, PR,R

1[ ]vfptAveraged Volume Fraction

A, C, M, P, PR,R

1[K]averaged temperatureAveraged Temperature

A, C, M, P, PR,R





1[ ]averaged mfAveraged Mass Fraction a

A, C, M, P, PR,R

2[s]averaged pttimeAveraged Particle Time

A, C, M, P, PR,R

2[m]averaged mean particlediameter

Averaged Mean Particle Diameter (D43)

A, C, M, P, PR,R

2[m]averaged arithmeticmean particle diameter

Averaged Arithmetic Mean Particle Diameter (D10)

A, C, M, P, PR,R

2[m]averaged surface meanparticle diameter

Averaged Surface Mean Particle Diameter (D20)

A, C, M, P, PR,R

2[m]averaged volume meanparticle diameter

Averaged Volume Mean Particle Diameter (D30)

A, C, M, P, PR,R

2[m]averaged sauter meanparticle diameter

Averaged Sauter Mean Particle Diameter (D32)

A, C, M, P, PR,R

2[m]averaged mass meanparticle diameter

Averaged Mass Mean Particle Diameter (D43)

A, C, M, P, PR,R

2[s^-1]averaged particlenumber rate

Averaged Particle Number Rate

A, C, M, P, PR,R

For simulations with the particle wall film model activated, the following additional vertex variables areavailable:

1[ ]vfptwAveraged Volume Fraction Wall

A, C, M, P, PR,R

1[K]averaged filmtemperature

Averaged Film Temperature

A, C, M, P, PR,R

aThis variable takes the following form: <Particle Type>.<Particle Component>.<Variable Name>

Variable CalculationsParticle vertex variables are calculated using the following averaging procedure:

(Eq. 5.1)= ∑∑

Φ PΔt m N ΦΔt m N

( · )( · )

P P P

P P

With:

67




• Σ: Sum over all particles and time steps in a control volume

• Δ t: Particle integration time step

• N· P: Particle number rate

• mP: Particle mass

• Φ: Particle quantity

Slightly different averaging procedures apply to particle temperature and particle mass fractions:

Averaged Particle Temperature

(Eq. 5.2)=∑

∑Φ P

Δt m N c T

Δt m N c( )

( )·

·P P P P P

P P P P

,

,

With:

Averaged Mass Fraction

• cP P, : Particle specific heat capacity

• TP: Particle temperature

(Eq. 5.3)=∑

∑Φ P

Δt m N

Δt m N( )·

( · )c P P

P P

,

With:

• mc P, : Mass of species c in the particle

Due to the discrete nature of particles, vertex variables may show an unsmooth spatial distribution, which may leadto robustness problems. To reduce possible problems a smoothing option is available. For details, see Vertex VariableSmoothing in the CFX documentation.

Particle Boundary Vertex VariablesParticle-boundary vertex variables are particle variables that are defined on the vertices of domain boundaries. Theyare normalized with the face area of the corresponding boundary control volume.

You can use these variables to color boundaries and to compute average or integrated values of the correspondingparticle quantities.

You cannot use these variables in CEL expressions or User Fortran, and you cannot monitor them during a simulation.

AvailabilityUnitsLong Variable Name

Available at inlet, outlet, openings and interfaces:

2[kg m^-2 s^-1]Mass Flow Density

B, R

2[kg m^-1 s^-2]Momentum Flow Density

B, R

2[kg s^-3]Energy Flow Density

B, R

Available at walls only:

2[kg m^-1 s^-2]Wall Stress

B, R

2[kg m^-2 s^-1]Wall Mass Flow Density

B, R




AvailabilityUnitsLong Variable Name

2[kg m^-2 s^-1]Erosion Rate Density

B, R

Available in transient runs:

2[kg m^-2]Time Integrated Mass Flow Density

B, R

[kg m^-1 s^-1]Time Integrated Momentum Flow Density

2[kg s^-2]Time Integrated Energy Flow Density

B, R

2[kg m^-2]Time Integrated Wall Mass Flow Density

B, R

2[kg m^-2]Time Integrated Erosion Rate Density

B, R

Particle RMS VariablesFor some applications, it may be necessary to not only provide the mean values of particle quantities, but also theirstandard deviation in the form of particle RMS variables. Similar to particle vertex variables, these variables arealso defined at the vertices of the fluid calculation. Particle RMS variables are available for use in CEL expressionsand User Fortran; they can be monitored during a simulation, and are available for general post-processing inCFD-Post. Additionally, particle RMS variables can be used in the same way as particle track variables as input toparticle User Fortran and for coloring tracks.

By default, particle RMS variables are not written to the results file; unless, they have been explicitly requested bythe user (selected from the Extra Output Variables List in the Output Control section of CFX-Pre, usage in aCEL expression or in User Fortran) or if the stochastic particle collision model is used in a simulation.

The following particle variables are available as field variables, particularly useful for simulations that use thestochastic particle collision model:


1[m s^-1]rms velocityRMS Velocity

A, C, M, P, PR, R

1[K]rms temperatureRMS Temperature

A, C, M, P, PR, R

3[m]rms mean particlediameter

RMS Mean Particle Diameter

A, C, M, P, PR, R

3[s^-1]rms particle numberrate

RMS Particle Number Rate

A, C, M, P, PR, R

Variable CalculationsParticle RMS variables are calculated using the following procedure:

(Eq. 5.4)= + ′′

= ′′ = − = −

Φ Φ Φ

Φ Φ Φ Φ Φ Φ( )rms2 2 2 2

With:

69




• Φ: Instantaneous particle quantity

• Φ : Average particle quantity

• ′′Φ : Fluctuating particle quantity

• Φ2: Average of square of particle quantity

• Φ 2: Square of average of particle quantity

A smoothing option, as available for particle vertex variables, is available for particle RMS variables. For details,see Vertex Variable Smoothing in the CFX documentation.

Miscellaneous VariablesVariable names in bold are not output to CFD-Post.

In the Availability column:

• A number represents the user level (1 indicates that the variable appears in default lists, 2 and 3 indicate that

the variable appears in extended lists that you see when you click )

• A indicates the variable is available for mesh adaption

• C indicates the variable is available in CEL

• DT indicates the variable is available for data transfer to ANSYS

• M indicates the variable is available for monitoring

• P indicates the variable is available for particle user routine argument lists

• PR indicates the variable is available for particle results

• R indicates the variable is available to be output to the results, transient results, and backup files

• TS indicates the variable is available for transient statistics


Long Variable Name

2[ ]aspect ratioAspect Ratio

C, M, R, TS

1[ ]autoignitionAutoignition

A, C, M, R, TS

Similar to wallscale, this variable

3

C, M, R, TS

[ ]bnd scaleBoundary Scale

is used forcontrolling meshstiffness nearboundaries formoving meshproblems.

2[K]burnt TabsBurnt Absolute Temperature

A, C, M, R, TS

2[kg m^-3]burnt densityBurnt Density

A, C, M, R, TS

Negative absolutevalues clipped forcavitation

1

M, R, TS

[Pa]pclipClipped Pressure



Miscellaneous Variables


Long Variable Name

2[ ]sfcConservative Size Fraction

A, C, M, R, TS

2[ ]courantCourant Number

C, M, R, TS

2[ ]csfCumulative Size Fraction

A, C, M, R, TS

1jcurCurrent Density

C, M, R, TS

2diffdynDynamic Diffusivity

C, M, P, R, TS

1elecElectric Field

C, M, R, TS

1epotElectric Potential

C, M, R, TS

3conelecElectrical Conductivity

C, M, R, TS

3permelecElectrical Permittivity

C, M, R, TS

3bfemagElectromagnetic Force Density

R

2[ ]equivratioEquivalence Ratio

A, C, M, R, TS

External magneticinduction field

1

M, R, TS

[ ]bmagextExternal Magnetic Induction

specified by theuser.

3[ ]sstbf1First Blending Function for BSLand SST model C, M, R, TS

3[ ]sstbf2Second Blending Function forSST model C, M, R, TS

Combustion withflame surfacedensity models.

1

A, C, M, R, TS

[m^-1]fsdFlame Surface Density

Combustion withflame surfacedensity models.

2

A, C, M, R, TS

spfsdSpecific Flame Surface Density

3freqFrequency

C

71





Long Variable Name

Residual materialmodel or exhaust

1

A, C, M, R, TS

[ ]trfuelFuel Tracer

gas recirculation(EGR)

1[m^2 s^-2]grantempGranular Temperature

A, C, M, R, TS

2[ ]groupiGroup I Index

C

2[ ]groupjGroup J Index

C

2diamiGroup I Diameter

C

2diamjGroup J Diameter

C

2massiGroup I Mass

C

2massjGroup J Mass

C

2massi lowerGroup I Lower Mass

C

2massj lowerGroup J Lower Mass

C

2massi upperGroup I Upper Mass

C

2massj upperGroup J Upper Mass

C

2[ ]ignfrcIgnition Delay Elapsed Fraction

A, C, M, R, TS

2[s]tigndelayIgnition Delay Time

A, C, M, R, TS

3[s]particle integrationtimestep

Particle Integration Timestep

P

entry>

⎛⎝⎜

⎞⎠⎟

⎛⎝⎜

⎞⎠⎟

∂∂ρρps

1

2

C, M, R

entry>

[m s^2 kg^-1]

compisoSIsentropic Compressibility

2[ ]icompeffIsentropic CompressionEfficiency C, M, R, TS





Long Variable Name

2[ ]iexpeffIsentropic Expansion Efficiency

C, M, R, TS

2htotisenIsentropic Total Enthalpy

C, M, R, TS

2enthisenIsentropic Static Enthalpy

C, M, R, TS

− ∂∂ρρT

p

1entry>

2

C, M, R

[K^-1] compisoPIsobaric Compressibility

∂∂ρρpT

12

C, M, R

[m s^2 kg^-1 ]compisoTIsothermal Compressibility

1[ ]dynmcLES Dynamic Model Coefficient

A, C, M, P, R, TS

2[m s^-1]velburnlamLaminar Burning Velocity

A, C, R, TS

2lighthill stresstensor

Lighthill Stress

A, C, M, R, TS

1bmagMagnetic Induction

C, M, R, TS

2hmagMagnetic Field

C, M, R, TS

1bpotMagnetic Vector Potential

C, M, R, TS

3permmagMagnetic Permeability

C, M, R, TS

1bmagextExternal Magnetic Induction

C, M, R, TS

2mffluxMass Flux

R

2[m^2 s^-1]diffmeshMesh Diffusivity

C, M, R, TS

Normal area vectors.2[ ]normareaNormal Area

C

3forcetdenTotal Force Density

DT

73





Long Variable Name

Based on relativeframe total enthalpy.

2

A, C, M, P, R, TS

ptotrelTotal Pressure in Rel Frame

2[m s^-1]velburnturbTurbulent Burning Velocity

A, C, R, TS

1meshvelMesh Velocity

C, M, R, TS

3[s^-1]mixscldsMixture Fraction ScalarDissipation Rate A, C, M, R, TS

2reacrateMolar Reaction Rate

C, R, TS

Nonclipped absolutepressure for

3

A, C, M, R, TS

pabsncNonclipped Absolute Pressure

cavitation source.This is written to the.res file for allcases that havecavitation.

Nonclipped densityfor cavitation source

2

C

[kg m^-3]densityncNonclipped Density

2[ ]normalNormal Vector

C

2[ ]orthfactminOrthogonality FactorMinimum C, M, R, TS

2[ ]orthfact Orthogonality Factor

C, M, R, TS

2orthangleminOrthogonality AngleMinimum C, M, R, TS

2orthangleOrthogonality Angle

C, M, R, TS

2[ ]ptlaParticle Laplace Number

P

3[s^-1]particle number rateParticle Number Rate

P

3[ ]particle numberdensity

Particle Number Density

A, C, M, R, TS

2pttimeParticle Time

A, C, M, P, PR, R, TS

2ptdistParticle Traveling Distance

P





Long Variable Name

2[ ]ptsttParticle Turbulent StokesNumber P

2[ ]pcompeffPolytropic CompressionEfficiency C, M, R, TS

2[ ]pexpeffPolytropic Expansion Efficiency

C, M, R, TS

2htotpolyPolytropic Total Enthalpy

C, M, R, TS

2enthpolyPolytropic Static Enthalpy

C, M, R, TS

For premixed orpartially premixedcombustion.

1

A, C, M, R, TS

[ ]reacprogReaction Progress


2

A, C, M, R, TS

[ ]wreacprogWeighted Reaction Progress


3

A, C, R, TS

wreacprogsrcWeighted Reaction ProgressSource


1

A, C, M, R, TS

[ ]mfresidResidual Products Mass Fraction



2

A, C, M, R, TS

[ ]molfresidResidual Products MolarFraction


3[ ]restitutioncoefficient

Restitution Coefficient

C, M, R, TS

2rotvelRotation Velocity

C, R, TS

2rotenergyRotational Energy

C, R, TS

2ustarShear Velocity

C

1[ ]sfSize Fraction

A, C, M, R, TS

3[kg m^-1 s^-1]solid bulk viscositySolid Bulk Viscosity

C, M, R, TS

3[Pa]solid pressureSolid Pressure

75





Long Variable Name

A, C, M, R, TS

3[ ]solid pressuregradient

Solid Pressure Gradient

C, M, R, TS

3[kg m^-1 s^-1]solid shearviscosity

Solid Shear Viscosity

C, M, R, TS

3entropyStatic Entropy

A, C, M, P, R, TS

1TvarTemperature Variance

A, C, M, R, TS

2trunTime This Run

C

1bnddisptotTotal Boundary Displacement

C, DT, M, R, TS

2[kg m^-3]dentotTotal Density

A, C, M, R

2[kg m^-3]dentotstnTotal Density in Stn Frame

A, C, M, R

2[kg m^-3]dentotrelTotal Density in Rel Frame

A, C, M, R

3forcetTotal Force

DT

2[K]unburnt TabsUnburnt Absolute Temperature

A, C, M, R, TS

2[kg m^-3]unburnt densityUnburnt Density

A, C, M, R, TS

2[W m^-1 K^-1]unburnt condUnburnt Thermal Conductivity

A, C, M, R, TS

2[J kg^-1 K^-1]unburnt CpUnburnt Specific Heat Capacityat Constant Pressure A, C, M, R, TS

2[ ]volporVolume Porosity

C, M, R, TS

3volcvolVolume of Finite Volumes

C, R, TS

Note that Vorticityis the same asVelocity.Curl.

2

A, C, M, R, TS

vorticityVorticity

2vortstnVorticity in Stn Frame





Long Variable Name

A, C, M, R, TS

2htcoWall External Heat TransferCoefficient R, TS

2[K]tnwWall Adjacent Temperature

C, DT, R, TS

2[m]wall distanceWall Distance

A, C, M, P, R, TS

User-specifiedexternal wall

2

DT, R, TS

[K]tnwoWall External Temperature

temperature for heattransfer coefficientboundaryconditions.

2[m]film thicknessWall Film Thickness

C, R

2htcWall Heat Transfer Coefficient

C, R, TS

3QwallFlowWall Heat Flow

C, DT, R, TS

2nwallvelWall Normal Velocity

C, R, TS

3wall scaleWall Scale

R, M, TS

3waveloWavelength in Vacuum

C

3wavenoWavenumber in Vacuum

C

2[m^-3]spdropnNormalized Droplet Number

C, M, R, TS

1spdropDroplet Number

C, M, R, TS

1dynamic bulkviscosity

Dynamic Bulk Viscosity

A, C, M, R, TS

2[ ]vftTotal MUSIG Volume Fraction

A, C, M, R, TS

2[ ]vfsSmoothed Volume Fraction

A, C, M, R, TS

77





Long Variable Name

Temperature abovesaturation

3

C

TsuperheatTemperature Superheating

Temperature belowsaturation

3

C

TsubcoolTemperature Subcooling




Chapter 6. ANSYS FLUENT Field VariablesListed by Category

By default, CFD-Post does not modify the variable names in the ANSYS FLUENT file. If you want to use all ofthe embedded CFD-Post macros and calculation options, you need to convert variable names to CFX types. Youcan convert the variable names to CFX variable names by selecting the Translate variable names to CFX-Solverstyle names check box in the Edit > Options > Files menu. Translation is carried out according to the tables thatfollow, which list the ANSYS FLUENT field variables and gives the equivalent ANSYS CFX variable, where oneexists.

The following restrictions apply to marked variables:

available only for 2D flows2d

available only for 2D axisymmetric flows (with or without swirl)2da

available only for 2D axisymmetric swirl flows2dasw

available only for 3D flows3d

available only for broadband noise source modelsbns

node values available at boundariesbnv

available only in the density-based solverscpl

available only for cell values (Node Values option turned off)cv

available only when the DES turbulence model is useddes

not available with full multicomponent diffusiondil

available only when the discrete ordinates radiation model is useddo

available only for coupled discrete phase calculationsdpm

available only when the discrete transfer radiation model is useddtrm

available only with the Ffowcs Williams and Hawkings acoustics modelfwh

available only for energy calculationse

available only with the EDC model for turbulence-chemistry interactionedc

available also when the Eulerian multiphase model is usedemm

available only with the enhanced wall treatmentewt

available only if a granular phase is presentgran

available only when the mixture contains waterh2o

available only when the ideal gas law is enabled for densityid

available only when one of the k-epsilon turbulence models is usedke

available only when one of the k-omega turbulence models is usedkw

available only when the LES turbulence model is usedles

available only when the melting and solidification model is usedmelt

available only when the multiphase mixture model is usedmix

available only for multiphase modelsmp

available only for NOx calculationsnox

not available in parallel solversnp

uses explicit node value functionnv

available only in parallel solversp

available only when the P-1 radiation model is usedp1

79



available only for non-premixed combustion calculationspdf

available only for premixed combustion calculationspmx

available only for partially premixed combustion calculationsppmx

available only when the Rosseland radiation model is usedr

available only for radiation heat transfer calculationsrad

available only for finite-rate reactionsrc

available only when the Reynolds stress turbulence model is usedrsm

available only when the surface-to-surface radiation model is useds2s

available only when the Spalart-Allmaras turbulence model is usedsa

available only in the pressure-based solverseg

available only for species calculationssp

available only for surface reactionssr

available only when the solar model is usedsol

available only for soot calculationssoot

available only with data sampling for unsteady statisticsstat

available only for stiff chemistry calculationsstcm

available only for turbulent flowst

available only when a turbomachinery topology has been definedturbo

available only when a user-defined memory is usedudm

available only when a user-defined scalar is useduds

available only for viscous flowsv

Table 6.1. Pressure and Density Categories

CFX VariableANSYS FLUENT VariableCategory

PressureStatic Pressure (bnv)Pressure...

Pressure CoefficientPressure Coefficient

Dynamic PressureDynamic Pressure

Absolute PressureAbsolute Pressure (bnv)

Total Pressure in Stn FrameTotal Pressure (bnv)

Relative Total PressureRelative Total Pressure

DensityDensityDensity...

DensityDensity All



Table 6.2. Velocity Category


Velocity in Stn FrameVelocity Magnitude (bnv)Velocity...

Velocity in Stn Frame uX Velocity (bnv)

Velocity in Stn Frame vY Velocity (bnv)

Velocity in Stn Frame wZ Velocity (3d, bnv)

Velocity CircumferentialSwirl Velocity (2dasw, bnv)

Velocity AxialAxial Velocity (2da or 3d)

Velocity RadialRadial Velocity

Stream FunctionStream Function (2d)

Velocity CircumferentialTangential Velocity

Mach Number in Stn FrameMach Number (id)

VelocityRelative Velocity Magnitude (bnv)

Velocity uRelative X Velocity (bnv)

Velocity vRelative Y Velocity (bnv)

Velocity wRelative Z Velocity (3d, bnv)

Velocity AxialRelative Axial Velocity (2da)

Velocity RadialRelative Radial Velocity (2da)

Velocity CircumferentialRelative Swirl Velocity (2dasw, bnv)

Velocity CircumferentialRelative Tangential Velocity

Mach NumberRelative Mach Number (id)

Mesh Velocity XGrid X-Velocity (nv)

Mesh Velocity YGrid Y-Velocity (nv)

Mesh Velocity ZGrid Z-Velocity (3d, nv)

Velocity AngleVelocity Angle

Velocity AngleRelative Velocity Angle

Vorticity in Stn FrameVorticity Magnitude (v)

Vorticity in Stn Frame XX-Vorticity (v, 3d)

Vorticity in Stn Frame YY-Vorticity (v, 3d)

Vorticity in Stn Frame ZZ-Vorticity (v, 3d)

Cell Reynolds NumberCell Reynolds Number (v)

Reference Velocity (Preconditioning)Preconditioning Reference Velocity (cpl)

81



Table 6.3. Temperature, Radiation, and Solidification/Melting Categories


TemperatureStatic Temperature (e, bnv, nv)Temperature...

Total Temperature in Stn FrameTotal Temperature (e, nv)

Static EnthalpyEnthalpy (e, nv)

Total TemperatureRelative Total Temperature (e)

RothalpyRothalpy (e, nv)

Fine Scale TemperatureFine Scale Temperature (edc, nv, e)

Wall Temperature Outer SurfaceWall Temperature (Outer Surface) (e, v)

Wall Temperature Inner SurfaceWall Temperature (Inner Surface) (e, v)

Inner Wall TemperatureInner Wall Temperature

Total Enthalpy in Stn FrameTotal Enthalpy (e)

Total Enthalpy DeviationTotal Enthalpy Deviation (e)

Static EntropyEntropy (e)

Total Energy in Stn FrameaTotal Energy (e)

Internal EnergyInternal Energy (e)

Absorption CoefficientAbsorption Coefficient (r, p1, do, or dtrm)Radiation...

Scattering CoefficientScattering Coefficient (r, p1, or do)

Refractive IndexRefractive Index (do)

Radiation TemperatureRadiation Temperature (p1 or do)

Incident RadiationIncident Radiation (p1 or do)

<Band n>.Incident RadiationIncident Radiation (Band n) (do (non-gray))

Surface Cluster IDSurface Cluster ID (s2s)

<component>.Mass FractionLiquid Fraction (melt)Solidification/Melting

Contact ResistivityContact Resistivity (melt)

Pull Velocity XaX Pull Velocity (melt (if calculated))

Pull Velocity YaY Pull Velocity (melt (if calculated))

Pull Velocity ZaZ Pull Velocity (melt (if calculated), 3d)

Pull Velocity AxialaAxial Pull Velocity (melt (if calculated), 2da)

Pull Velocity RadialaRadial Pull Velocity (melt (if calculated), 2da)

Pull Velocity CircumferentialaSwirl Pull Velocity (melt (if calculated), 2dasw)

aANSYS CFD-Post naming convention



Table 6.4. Turbulence Category


Turbulent Kinetic EnergyTurbulent Kinetic Energy (k) (ke, kw, or rsm;bnv, nv, or emm)

Turbulence...

Reynolds Stress uuUU Reynolds Stress (rsm; emm)

Reynolds Stress vvVV Reynolds Stress (rsm; emm)

Reynolds Stress wwWW Reynolds Stress (rsm; emm)

Reynolds Stress uvUV Reynolds Stress (rsm; emm)

Reynolds Stress uwUW Reynolds Stress (rsm, 3d; emm)

Reynolds Stress vwVW Reynolds Stress (rsm, 3d; emm)

Turbulence IntensityTurbulence Intensity (ke, kw, or rsm)

Turbulence Eddy DissipationTurbulent Dissipation Rate (Epsilon) (ke orrsm; bnv, nv, or emm)

Turbulence Eddy FrequencySpecific Dissipation Rate (Omega) (kw)

Turbulence Kinetic Energy ProductionaProduction of k (ke, kw, or rsm; emm)

Eddy Viscosity (modified)Modified Turbulent Viscosity (sa)

Eddy ViscosityTurbulent Viscosity (sa, ke, kw, rsm, or des)

Effective ViscosityEffective Viscosity (sa, ke, kw, rsm, or des;emm)

Eddy Viscosity RatioTurbulent Viscosity Ratio (ke, kw, rsm, sa, ordes; emm)

Kinetic Energy (subgrid)Subgrid Kinetic Energy (les)

Eddy Viscosity (subgrid)Subgrid Turbulent Viscosity (les)

(unavailable)Subgrid Effective Viscosity (les)

Eddy Viscosity Ratio (subgrid)Subgrid Turbulent Viscosity Ratio (les)

(unavailable)Subgrid Filter Length (les)

Effective Thermal ConductivityEffective Thermal Conductivity (t, e)

Effective Prandtl NumberEffective Prandtl Number (t, e)

YstarWall Ystar (ke, kw, or rsm)

YplusWall Yplus (t)

Turbulent Reynolds NumberTurbulent Reynolds Number (Re_y) (ke or rsm;ewt)

Relative Length Scale (DES)Relative Length Scale (DES) (des)

83



Table 6.5. Species, Reactions, Pdf, and Premixed Combustion Categories


<Species-n>.Mass FractionMass fraction of species-n (sp, pdf, or ppmx;nv)

Species...

<Species-n>.Mole FractionMole fraction of species-n (sp, pdf, or ppmx)

<Species-n>.Molar ConcentrationMolar Concentration of species-n (sp, pdf, orppmx)

<Species-n>.Laminar Diffusion CoefficientLam Diff Coef of species-n (sp, dil)

<Species-n>.Effective Diffusion Diffusivity aEff Diff Coef of species-n (t, sp, dil)

<Species-n>.Thermal Diffusion CoefficientThermal Diff Coef of species-n (sp)

<Species-n>.Static EnthalpyEnthalpy of species-n (sp)

<Species-n>.Source Termaspecies-n Source Term (rc, cpl)

<Species-n>.Surface Deposition RateSurface Deposition Rate of species-n (sr)

<Species-n>.Surface CoverageaSurface Coverage of species-n (sr)

Relative HumidityRelative Humidity (sp, pdf, or ppmx; h2o)

Time Step ScaleTime Step Scale (sp, stcm)

<Species-n>.Fine Scale Mass FractionFine Scale Mass fraction of species-n (edc)

Fine Scale Transfer RateFine Scale Transfer Rate (edc)

1-Fine Scale Volume Fraction1-Fine Scale Volume Fraction (edc)

<Reaction-n>.Molar Reaction RateRate of Reaction-n (rc)Reactions...

<Reaction-n>.Molar Arrhenius Reaction RateaArrhenius Rate of Reaction-n (rc)

<Reaction-n>.Molar Turbulent Reaction RateaTurbulent Rate of Reaction-n (rc, t)

Mean FractionMean Mixture Fraction (pdf or ppmx; nv)Pdf...

Secondary Mixture FractionaSecondary Mean Mixture Fraction (pdf orppmx; nv)

Mixture Fraction VarianceMixture Fraction Variance (pdf or ppmx; nv)

Secondary Mixture Fraction VarianceaSecondary Mixture Fraction Variance (pdf orppmx; nv)

Fvar ProdFvar Prod (pdf or ppmx)

(unavailable)Fvar2 Prod (pdf or ppmx)

Scalar DissipationScalar Dissipation (pdf or ppmx)

Reaction ProgressProgress Variable (pmx or ppmx; nv)PremixedCombustion... Damkohler NumberaDamkohler Number (pmx or ppmx)

Stretch FactoraStretch Factor (pmx or ppmx)

Turbulent Flame SpeedaTurbulent Flame Speed (pmx or ppmx)

TemperatureStatic Temperature (pmx or ppmx)

Product Formation RateaProduct Formation Rate (pmx or ppmx)

Laminar Flame SpeedaLaminar Flame Speed (pmx or ppmx)

Critical Strain RateaCritical Strain Rate (pmx or ppmx)

Adiabatic Flame Temperature aAdiabatic Flame Temperature (pmx or ppmx)

Unburnt Fuel Mass FractionaUnburnt Fuel Mass Fraction (pmx or ppmx)



Table 6.6. NOx, Soot, and Unsteady Statistics Categories


NO.Mass FractionMass fraction of NO (nox)NOx...

HCN.Mass FractionMass fraction of HCN (nox)

NH3.Mass FractionMass fraction of NH3 (nox)

N2O.Mass FractionMass fraction of N2O (nox)

NO.Molar FractionMole fraction of NO (nox)

HCN.Molar FractionMole fraction of HCN (nox)

NH3.Molar FractionMole fraction of NH3 (nox)

N2O.Molar FractionMole fraction of N2O (nox)

NO.DensityNO Density (nox)

HCN.DensityHCN Density (nox)

NH3.DensityNH3 Density (nox)

N2O.DensityN2O Density (nox)

Temperature VarianceVariance of Temperature (nox)

Species VarianceaVariance of Species (nox)

Species 1 VarianceaVariance of Species 1 (nox)

Species 2 VarianceaVariance of Species 2 (nox)

NO Source aRate of NO (nox)

Thermal NO.Molar Reaction RateRate of Thermal NO (nox)

Prompt NO.Molar Reaction RateaRate of Prompt NO (nox)

Fuel NO.Molar Reaction Rate aRate of Fuel NO (nox)

N2OPath.Molar Reaction Rate aRate of N2OPath NO (nox)

Reburn NO.Molar Reaction RateaRate of Reburn NO (nox)

SNCR NO.Molar Reaction RateaRate of SNCR NO (nox)

User NO.Molar Reaction Rate aRate of USER NO (nox)

Soot Mass FractionMass fraction of soot (soot)Soot...

Soot Nuclei Specific ConcentrationMass fraction of Nuclei (soot)

Soot Molar FractionaMole fraction of soot (soot)

Soot.DensitySoot Density (soot)

Soot Mass SourceaRate of Soot (soot)

Soot Nuclei SourceaRate of Nuclei (soot)

<variable>.TrnavgMean quantity-n (stat)UnsteadyStatistics... <variable>.TrnrmsRMS quantity-n (stat)

85



Table 6.7. Phases, Discrete Phase Model, Granular Pressure, and Granular TemperatureCategories


<phase>.Volume FractionVolume fraction (mp)Phases...

<particle>.Particle Mass SourceDPM Mass Source (dpm)Discrete PhaseModel... <particle>.Particle Erosion Rate Density aDPM Erosion (dpm, cv)

<particle>.Particle Wall Mass Flow DensityaDPM Accretion (dpm, cv)

<particle>.Particle Momentum Source XDPM X Momentum Source (dpm)

<particle>.Particle Momentum Source YDPM Y Momentum Source (dpm)

<particle>.Particle Momentum Source ZDPM Z Momentum Source (dpm, 3d)

<particle>.Particle Swirl Momentum SourceDPM Swirl Momentum Source (dpm, 2dasw)

<particle>.Particle Sensible Enthalpy SourceDPM Sensible Enthalpy Source (dpm, e)

<particle>.Particle Energy SourceDPM Enthalpy Source (dpm, e)

<particle>.Particle Absorption CoefficientDPM Absorption Coefficient (dpm, rad)

<particle>.Particle Radiative EmissionDPM Emission (dpm, rad)

<particle>.Particle Radiative Scattering aDPM Scattering (dpm, rad)

Particle BurnoutDPM Burnout (dpm, sp, e)

Particle Evaporation-DevolatilizationDPM Evaporation/Devolatilization (dpm, sp,e)

<particle>.Volume FractionDPM Concentration (dpm)

<Species-n>.Particle Mass SourceDPM species-n Source (dpm, sp, e)

<phase>.Granular PressureaGranular Pressure (emm, gran)Granular Pressure...

<phase>.Granular TemperatureGranular Temperature (emm, gran)GranularTemperature...



Table 6.8. Properties, Wall Fluxes, User Defined Scalars, and User Defined MemoryCategories


Dynamic ViscosityMolecular Viscosity (v)Properties...

Mean Particle DiameterDiameter(mix, emm)

<phase>.Granular Conductivity aGranular Conductivity (mix, emm, gran)

Thermal ConductivityThermal Conductivity (e, v)

Specific Heat Capacity at Constant PressureSpecific Heat (Cp) (e)

Specific Heat RatioaSpecific Heat Ratio (gamma) (id)

R Gas ConstantGas Constant (R) (id)

Prandtl NumberaMolecular Prandtl Number (e, v)

Molar MassaMean Molecular Weight (seg, pdf)

Local Speed of Sound aSound Speed (id)

Wall ShearWall Shear Stress (v, cv, emm)Wall Fluxes...

Wall Shear XX-Wall Shear Stress (v, cv, emm)

Wall Shear YY-Wall Shear Stress (v, cv, emm)

Wall Shear ZZ-Wall Shear Stress (v, 3d, cv, emm)

Wall Shear AxialAxial-Wall Shear Stress (2da, cv)

Wall Shear RadialRadial-Wall Shear Stress (2da, cv)

Wall Shear CircumferentialSwirl-Wall Shear Stress (2dasw, cv)

Skin Friction CoefficientSkin Friction Coefficient (v, cv, emm)

Wall Heat FluxTotal Surface Heat Flux (e, v, cv)

Wall Radiative Heat FluxRadiation Heat Flux (rad, cv)

Solar Heat FluxSolar Heat Flux (sol, cv)

<Band-n>.Absorbed Radiation FluxAbsorbed Radiation Flux (Band-n) (do,cv)

Absorbed Visible Solar FluxAbsorbed Visible Solar Flux (sol, cv)

Absorbed IR Solar FluxAbsorbed IR Solar Flux (sol, cv)

<Band-n>.Reflected Radiation FluxReflected Radiation Flux (Band-n) (do, cv)

Reflected Visible Solar FluxReflected Visible Solar Flux (sol, cv)

Reflected IR Solar FluxReflected IR Solar Flux (sol, cv)

<Band-n>.Transmitted Radiation FluxTransmitted Radiation Flux (Band-n) (do, cv)

Transmitted Visible Solar FluxTransmitted Visible Solar Flux (sol, cv)

Transmitted IR Solar FluxTransmitted IR Solar Flux (sol, cv)

<Band-n>.Beam Irradiation FluxBeam Irradiation Flux (Band-n) (do, cv)

Surface Incident RadiationSurface Incident Radiation (do, dtrm, or s2s;cv)

Surface Heat Transfer Coef.Surface Heat Transfer Coef. (e, v, cv)

Wall Func. Heat Tran. Coef.Wall Func. Heat Tran. Coef. (e, v, cv)

Surface Nusselt NumberSurface Nusselt Number (e, v, cv)

Surface Stanton NumberSurface Stanton Number (e, v, cv)

<Scalar-n>Scalar-n (uds)User-DefinedScalars... <Scalar-n>.Diffusion CoefficientDiffusion Coef. of Scalar-n (uds)

87




User Defined Memory <n>User Memory n (udm)User-DefinedMemory...

Table 6.9. Cell Info, Grid, and Adaption Categories


Cell PartitionCell Partition (np)Cell Info...

Active Cell PartitionActive Cell Partition (p)

Stored Cell PartitionStored Cell Partition (p)

Cell IdCell Id (p)

Cell Element TypeCell Element Type

Cell Zone TypeCell Zone Type

Cell Zone IndexCell Zone Index

Partition NeighborsPartition Neighbors

XX-Coordinate (nv)Grid...

YY-Coordinate (nv)

ZZ-Coordinate (3d, nv)

Axial CoordinateAxial Coordinate (nv)

Angular CoordinateAngular Coordinate (3d, nv)

Absolute Angular CoordinateAbs. Angular Coordinate (3d, nv)

Radial Angular CoordinateRadial Coordinate (nv)

X Surface Area

Y Surface Area

Z Surface Area (3d)

Face Area XX Face Area

Face Area YY Face Area

Face Area ZZ Face Area (3d)

Cell Equiangle SkewCell Equiangle Skew

Cell Equivolume SkewCell Equivolume Skew

Cell VolumeCell Volume

2d Cell Volume2D Cell Volume (2da)

Cell Wall DistanceCell Wall Distance

Face HandednessFace Handedness

Face Squish IndexFace Squish Index

Cell Squish IndexCell Squish Index



Table 6.10. Grid Category (Turbomachinery-Specific Variables) and Adaption Category


Meridional CoordinateMeridional Coordinate (nv, turbo)Grid...

Abs Meridional CoordinateAbs Meridional Coordinate (nv, turbo)

Spanwise CoordinateSpanwise Coordinate (nv, turbo)

Abs (H-C) Spanwise CoordinateAbs (H-C) Spanwise Coordinate (nv, turbo)

Abs (C-H) Spanwise CoordinateAbs (C-H) Spanwise Coordinate (nv, turbo)

Pitchwise CoordinatePitchwise Coordinate (nv, turbo)

Abs Pitchwise CoordinateAbs Pitchwise Coordinate (nv, turbo)

Adaption FunctionAdaption FunctionAdaption...

Adaption CurvatureAdaption Curvature

Adaption Space GradientAdaption Space Gradient

Adaption Iso-ValueAdaption Iso-Value

Existing ValueExisting Value

Boundary Cell DistanceBoundary Cell Distance

Boundary Normal DistanceBoundary Normal Distance

Boundary Volume DistanceBoundary Volume Distance (np)

Cell Volume ChangeCell Volume Change

Cell Surface AreaCell Surface Area

Cell WarpageCell Warpage

Cell ChildrenCell Children

Cell Refine LevelCell Refine Level

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Table 6.11. Residuals Category


Mass ImbalanceMass Imbalance (seg)Residuals...

Pressure ResidualPressure Residual (cpl)

Residual u VelocityX-Velocity Residual (cpl)

Residual v VelocityY-Velocity Residual (cpl)

Residual w VelocityZ-Velocity Residual (cpl, 3d)

Residual Axial-VelocityAxial-Velocity Residual (cpl, 2da)

Residual Radial-VelocityRadial-Velocity Residual (cpl, 2da)

Residual Circumferential-VelocitySwirl-Velocity Residual (cpl, 2dasw)

Residual TemperatureTemperature Residual (cpl, e)

<Species-n>.ResidualSpecies-n Residual (cpl, sp)

Time StepTime Step (cpl)

Pressure CorrectionPressure Correction (cpl)

u Velocity CorrectionX-Velocity Correction (cpl)

v Velocity CorrectionY-Velocity Correction (cpl)

w Velocity CorrectionZ-Velocity Correction (cpl, 3d)

Axial-Velocity CorrectionAxial-Velocity Correction (cpl, 2da)

Radial-Velocity CorrectionRadial-Velocity Correction (cpl, 2da)

Circumferential-Velocity CorrectionSwirl-Velocity Correction (cpl, 2dasw)

Temperature CorrectionTemperature Correction (cpl, e)

<Species-n>.CorrectionSpecies-n Correction (cpl, sp)



Table 6.12. Derivatives Category


Strain RateStrain Rate (v)Derivatives...

du-Velocity-dxdX-Velocity/dx

dv-Velocity-dxdY-Velocity/dx

dw-Velocity-dxdZ-Velocity/dx (3d)

dAxial-Velocity-dxdAxial-Velocity/dx (2da)

dRadial-Velocity-dxdRadial-Velocity/dx (2da)

dCircumferential-Velocity-dxdSwirl-Velocity/dx (2dasw)

d<Species-n>-dxd species-n/dx (cpl, sp)

du-Velocity-dydX-Velocity/dy

dv-Velocity-dydY-Velocity/dy

dw-Velocity-dydZ-Velocity/dy (3d)

dAxial-Velocity-dydAxial-Velocity/dy (2da)

dRadial-Velocity-dydRadial-Velocity/dy (2da)

dCircuferential-Velocity-dydSwirl-Velocity/dy (2dasw)

d<Species-n>-dyd species-n/dy (cpl, sp)

du-Velocity-dzdX-Velocity/dz (3d)

dv-Velocity-dzdY-Velocity/dz (3d)

dw-Velocity-dzdZ-Velocity/dz (3d)

d<Species-n>-dzd species-n/dz (cpl, sp, 3d)

dOmega-dxdOmega/dx (2dasw)

dOmega-dydOmega/dy (2dasw)

dp-dXdp-dX (seg)

dp-dYdp-dY (seg)

dp-dZdp-dZ (seg, 3d)

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Table 6.13. Acoustics Category


Surface dpdt RMSSurface dpdt RMS (fwh)Acoustics...

Acoustic Power Level (dB)Acoustic Power Level (dB) (bns)

Acoustic PowerAcoustic Power (bns)

Jet Acoustic Power Level (dB)Jet Acoustic Power Level (dB) (bns, 2da)

Jet Acoustic PowerJet Acoustic Power (bns, 2da)

Surface Acoustic Power Level (dB) (bns)

Surface Acoustic Power (bns)

Lilley's Self-Noise SourceLilley's Self-Noise Source (bns)

Lilley's Shear-Noise SourceLilley's Shear-Noise Source (bns)

Lilley's Total Noise SourceLilley's Total Noise Source (bns)

LEE Self-Noise X-SourceLEE Self-Noise X-Source (bns)

LEE Shear-Noise X-SourceLEE Shear-Noise X-Source (bns)

LEE Total Noise X-SourceLEE Total Noise X-Source (bns)

LEE Self-Noise Y-SourceLEE Self-Noise Y-Source (bns)

LEE Shear-Noise Y-SourceLEE Shear-Noise Y-Source (bns)

LEE Total Noise Y-SourceLEE Total Noise Y-Source (bns)

LEE Self-Noise Z-SourceLEE Self-Noise Z-Source (bns, 3d)

LEE Shear-Noise Z-SourceLEE Shear-Noise Z-Source (bns, 3d)

LEE Total Noise Z-SourceLEE Total Noise Z-Source (bns, 3d)

Alphabetical Listing of ANSYS FLUENT FieldVariables and Their Definitions

This section defines the ANSYS FLUENT field variables. For some variables (such as residuals) a general definitionis given under the category name, and variables in the category are not listed individually. When appropriate, theunit quantity is included, as it appears in the Set Units panel.

Variables A-CAbs (C-H) Spanwise Coordinate

(in the Grid... category) is the dimensional coordinate in the spanwise direction, from casing to hub. Its unitquantity is length.

Abs (H-C) Spanwise Coordinate(in the Grid... category) is the dimensional coordinate in the spanwise direction, from hub to casing. Its unitquantity is length.

Abs Meridional Coordinate(in the Grid... category) is the dimensional coordinate that follows the flow path from inlet to outlet. Its unitquantity is length.

Abs Pitchwise Coordinate(in the Grid... category) is the dimensional coordinate in the circumferential (pitchwise) direction. Its unitquantity is angle.

Absolute Pressure(in the Pressure... category) is equal to the operating pressure plus the gauge pressure. See Operating Pressurein the ANSYS FLUENT documentation for details. Its unit quantity is pressure.



Alphabetical Listing of ANSYS FLUENT Field Variables and Their Definitions

Absorbed Radiation Flux (Band-n)(in the Wall Fluxes... category) is the amount of radiative heat flux absorbed by a semi-transparent wall for aparticular band of radiation. Its unit quantity is heat-flux.

Absorbed Visible Solar Flux, Absorbed IR Solar Flux(in the Wall Fluxes... category) is the amount of solar heat flux absorbed by a semi-transparent wall for a visibleor infrared (IR) radiation.

Absorption Coefficient(in the Radiation... category) is the property of a medium that describes the amount of absorption of thermalradiation per unit path length within the medium. It can be interpreted as the inverse of the mean free path thata photon will travel before being absorbed (if the absorption coefficient does not vary along the path). The unitquantity for Absorption Coefficient is length-inverse.

Acoustic Power(in the Acoustics... category) is the acoustic power per unit volume generated by isotropic turbulence

It is available only when the Broadband Noise Sources acoustics model is being used. Its unit quantity ispower per volume.

Acoustic Power Level (dB)(in the Acoustics... category) is the acoustic power per unit volume generated by isotropic turbulence andreported in dB

It is available only when the Broadband Noise Sources acoustics model is being used.

Active Cell Partition(in the Cell Info... category) is an integer identifier designating the partition to which a particular cell belongs.In problems in which the grid is divided into multiple partitions to be solved on multiple processors using theparallel version of ANSYS FLUENT, the partition ID can be used to determine the extent of the various groupsof cells. The active cell partition is used for the current calculation, while the stored cell partition (the lastpartition performed) is used when you save a case file. See Partitioning the Grid Manually in the ANSYSFLUENT documentation for more information.

Adaption...includes field variables that are commonly used for adapting the grid. For information about solution adaption,see Partitioning the Grid Manually in the ANSYS FLUENT documentation.

Adaption Function(in the Adaption... category) can be either the Adaption Space Gradient or the Adaption Curvature, dependingon the settings in the Gradient Adaption panel. For instance, the Adaption Curvature is the undividedLaplacian of the values in temporary cell storage. To display contours of the Laplacian of pressure, for example,you first select Static Pressure, click the Compute (or Display) button, select Adaption Function, and finallyclick the Display button.

Adaption Iso-Value(in the Adaption... category) is the desired field variable function.

Adaption Space Gradient(in the Adaption... category) is the first derivative of the desired field variable.

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Variables A-C

Depending on the settings in the Gradient Adaption panel, this equation will either be scaled or normalized.Recommended for problems with shock waves (such as supersonic, inviscid flows). For more information, seeGradient Adaption Approach in the ANSYS FLUENT documentation.

Adaption Curvature(in the Adaption... category) is the second derivative of the desired field variable.

Depending on the settings in the Gradient Adaption panel, this equation will either be scaled or normalized.Recommended for smooth solutions (that is, viscous, incompressible flows). For more information, see GradientAdaption Approach in the ANSYS FLUENT documentation.

Adiabatic Flame Temperature(in the Premixed Combustion... category) is the adiabatic temperature of burnt products in a laminar premixed

flame ( in

Its unit quantity is temperature.

Arrhenius Rate of Reaction-n(in the Reactions... category) is given by:

where

represents the net effect of third bodies on the reaction rate. This term is given by

The reported value is independent of any particular species, and has units of kgmol/m^3-s.

To find the rate of production/destruction for a given species due to reaction , multiply the reported reaction

rate for reaction by the term , where is the molecular weight of species , and

and are the stoichiometric coefficients of species in reaction .

Angular Coordinate(in the Grid... category) is the angle between the radial vector and the position vector. The radial vector isobtained by transforming the default radial vector (y-axis) by the same rotation that was applied to the defaultaxial vector (z-axis). This assumes that, after the transformation, the default axial vector (z-axis) becomes thereference axis. The angle is positive in the direction of cross-product between reference axis and radial vector.

Abs. Angular Coordinate(in the Grid... category) is the absolute value of the Angular Coordinate defined above.

Axial Coordinate(in the Grid... category) is the distance from the origin in the axial direction. The axis origin and (in 3D)direction is defined for each cell zone in the Fluid or Solid panel. The axial direction for a 2D model is always



Variables A-C

the z direction, and the axial direction for a 2D axisymmetric model is always the x direction. The unit quantityfor Axial Coordinate is length.

Axial Pull Velocity(in the Solidification/Melting... category) is the axial-direction component of the pull velocity for the solidmaterial in a continuous casting process. Its unit quantity is velocity.

Axial Velocity(in the Velocity... category) is the component of velocity in the axial direction. (See Velocity Reporting Optionsin the ANSYS FLUENT documentation for details.) For multiphase models, this value corresponds to theselected phase in the Phase drop-down list. Its unit quantity is velocity.

Axial-Wall Shear Stress(in the Wall Fluxes... category) is the axial component of the force acting tangential to the surface due tofriction. Its unit quantity is pressure.

Beam Irradiation Flux (Band-b)

(in the Wall Fluxes... category) is specified as an incident heat flux ( ) for each wavelength band.

Boundary Cell Distance(in the Adaption... category) is an integer that indicates the approximate number of cells from a boundary zone.

Boundary Normal Distance(in the Adaption... category) is the distance of the cell centroid from the closest boundary zone.

Boundary Volume Distance(in the Adaption... category) is the cell volume distribution based on the Boundary Volume, Growth Factor,and normal distance from the selected Boundary Zones defined in the Boundary Adaption panel. See BoundaryAdaption in the ANSYS FLUENT documentation for details.

Cell Children(in the Adaption... category) is a binary identifier based on whether a cell is the product of a cell subdivisionin the hanging-node adaption process (value = 1) or not (value = 0).

Cell Element Type(in the Cell Info... category) is the integer cell element type identification number. Each cell can have one ofthe following element types:

triangle 1 tetrahedron 2 quadrilateral 3 hexahedron 4 pyramid 5 wedge 6

Cell Equiangle Skew(in the Grid... category) is a nondimensional parameter calculated using the normalized angle deviation method,and is defined as

where

• is the largest angle in the face or cell

• is the smallest angle in the face or cell

• is the angle for an equiangular face or cell (for example, 60 for a triangle and 90 for a square).

A value of 0 indicates a best case equiangular cell, and a value of 1 indicates a completely degenerate cell.Degenerate cells (slivers) are characterized by nodes that are nearly coplanar (collinear in 2D). Cell EquiangleSkew applies to all elements.

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Variables A-C

Cell Equivolume Skew(in the Grid... category) is a nondimensional parameter calculated using the volume deviation method, and isdefined as

where optimal-cell-size is the size of an equilateral cell with the same circumradius. A value of 0 indicates abest case equilateral cell and a value of 1 indicates a completely degenerate cell. Degenerate cells (slivers) arecharacterized by nodes that are nearly coplanar (collinear in 2D). Cell Equivolume Skew applies only totriangular and tetrahedral elements.

Cell Id(in the Cell Info... category) is a unique integer identifier associated with each cell.

Cell Info...includes quantities that identify the cell and its relationship to other cells.

Cell Partition(in the Cell Info... category) is an integer identifier designating the partition to which a particular cell belongs.In problems in which the grid is divided into multiple partitions to be solved on multiple processors using theparallel version of ANSYS FLUENT, the partition ID can be used to determine the extent of the various groupsof cells.

Cell Refine Level(in the Adaption... category) is an integer that indicates the number of times a cell has been subdivided in thehanging node adaption process, compared with the original grid. For example, if one quad cell is split into fourquads, the Cell Refine Level for each of the four new quads will be 1. If the resulting four quads are split again,the Cell Refine Level for each of the resulting 16 quads will be 2.

Cell Reynolds Number(in the Velocity... category) is the value of the Reynolds number in a cell. (Reynolds number is a dimensionlessparameter that is the ratio of inertia forces to viscous forces.) Cell Reynolds Number is defined as

where is density, is velocity magnitude, is the effective viscosity (laminar plus turbulent), and is

Cell Volume^1/2 for 2D cases and Cell Volume^1/3 in 3D or axisymmetric cases.

Cell Squish Index(in the Grid... category) is a measure of the quality of a mesh, and is calculated from the dot products of eachvector pointing from the centroid of a cell toward the center of each of its faces, and the corresponding facearea vector as

Therefore, the worst cells will have a Cell Squish Index close to 1.

Cell Surface Area(in the Adaption... category) is the total surface area of the cell, and is computed by summing the area of thefaces that compose the cell.

Cell Volume(in the Grid... category) is the volume of a cell. In 2D the volume is the area of the cell multiplied by the unitdepth. For axisymmetric cases, the cell volume is calculated using a reference depth of 1 radian. The unitquantity of Cell Volume is volume.



Variables A-C

2D Cell Volume(in the Grid... category) is the two-dimensional volume of a cell in an axisymmetric computation. For anaxisymmetric computation, the 2D cell volume is scaled by the radius. Its unit quantity is area.

Cell Volume Change(in the Adaption... category) is the maximum volume ratio of the current cell and its neighbors.

Cell Wall Distance(in the Grid... category) is the distribution of the normal distance of each cell centroid from the wall boundaries.Its unit quantity is length.

Cell Warpage(in the Adaption... category) is the square root of the ratio of the distance between the cell centroid and cellcircumcenter and the circumcenter radius:

Cell Zone Index(in the Cell Info... category) is the integer cell zone identification number. In problems that have more thanone cell zone, the cell zone ID can be used to identify the various groups of cells.

Cell Zone Type(in the Cell Info... category) is the integer cell zone type ID. A fluid cell has a type ID of 1, a solid cell has atype ID of 17, and an exterior cell (parallel solver) has a type ID of 21.

Contact Resistivity(in the Solidification/Melting... category) is the additional resistance at the wall due to contact resistance. It

is equal to , where is the contact resistance, is the liquid fraction, and is the cell

height of the wall-adjacent cell. The unit quantity for Contact Resistivity is thermal-resistivity.

Critical Strain Rate(in the Premixed Combustion... category) is a parameter that takes into account the stretching and extinction

of premixed flames ( in

Its unit quantity is time-inverse.

Custom Field Functions...are scalar field functions defined by you. You can create a custom function using the Custom Field FunctionCalculator panel. All defined custom field functions will be listed in the lower drop-down list. See CustomField Functions in the ANSYS FLUENT documentation for details.

Variables D-JDamkohler Number

(in the Premixed Combustion... category) is a nondimensional parameter that is defined as the ratio of turbulentto chemical time scales.

Density...includes variables related to density.

Density(in the Density... category) is the mass per unit volume of the fluid. Plots or reports of Density include onlyfluid cell zones. For multiphase models, this value corresponds to the selected phase in the Phase drop-downlist. The unit quantity for Density is density.

97



Variables D-J

Density All(in the Density... category) is the mass per unit volume of the fluid or solid material. Plots or reports of DensityAll include both fluid and solid cell zones. The unit quantity for Density All is density.

Derivatives...are the viscous derivatives. For example, dX-Velocity/dx is the first derivative of the x component of velocitywith respect to the x-coordinate direction. You can compute first derivatives of velocity, angular velocity, andpressure in the pressure-based solver, and first derivatives of velocity, angular velocity, temperature, and speciesin the density-based solvers.

Diameter(in the Properties... category) is the diameter of particles, droplets, or bubbles of the secondary phase selectedin the Phase drop-down list. Its unit quantity is length.

Diffusion Coef. of Scalar-n(in the User Defined Scalars... category) is the diffusion coefficient for the nth user-defined scalar transportequation. See the separate UDF manual for details about defining user-defined scalars.

Discrete Phase Model...includes quantities related to the discrete phase model. See Modeling Discrete Phase in the ANSYS FLUENTdocumentation for details about this model.

DPM Absorption Coefficient(in the Discrete Phase Model... category) is the absorption coefficient for discrete-phase calculations that

involve radiation, which is in

Its unit quantity is length-inverse.

DPM Accretion(in the Discrete Phase Model... category) is the accretion rate calculated at a wall boundary:

where is the mass flow rate of the particle stream, and is the area of the wall face where the particle

strikes the boundary. This item will appear only if the optional erosion/accretion model is enabled. SeeMonitoring Erosion/Accretion of Particles at Walls in the ANSYS FLUENT documentation for details. Theunit quantity for DPM Accretion is mass-flux.

DPM Burnout(in the Discrete Phase Model... category) is the exchange of mass from the discrete to the continuous phasefor the combustion law (Law 5) and is proportional to the solid phase reaction rate. The burnout exchange hasunits of mass-flow.

DPM Concentration(in the Discrete Phase Model... category) is the total concentration of the discrete phase. Its unit quantity isdensity.

DPM Emission(in the Discrete Phase Model... category) is the amount of radiation emitted by a discrete-phase particle perunit volume. Its unit quantity is heat-generation-rate.

DPM Enthalpy Source(in the Discrete Phase Model... category) is the exchange of enthalpy (sensible enthalpy plus heat of formation)from the discrete phase to the continuous phase. The exchange is positive when the particles are a source ofheat in the continuous phase. The unit quantity for DPM Enthalpy Source is power.



Variables D-J

DPM Erosion(in the Discrete Phase Model... category) is the erosion rate calculated at a wall boundary face:

where is the mass flow rate of the particle stream, is the impact angle of the particle path with the wall

face, is the function specified in the Wall panel, and is the area of the wall face where the

particle strikes the boundary. This item will appear only if the optional erosion/accretion model is enabled. SeeMonitoring Erosion/Accretion of Particles at Walls in the ANSYS FLUENT documentation for details. Theunit quantity for DPM Erosion is mass-flux.

DPM Evaporation/Devolatilization(in the Discrete Phase Model... category) is the exchange of mass, due to droplet-particle evaporation orcombusting-particle devolatilization, from the discrete phase to the evaporating or devolatilizing species. Ifyou are not using the non-premixed combustion model, the mass source for each individual species (DPMspecies-n Source, below) is also available; for non-premixed combustion, only this sum is available. The unitquantity for DPM Evaporation/Devolatilization is mass-flow.

DPM Mass Source(in the Discrete Phase Model... category) is the total exchange of mass from the discrete phase to the continuousphase. The mass exchange is positive when the particles are a source of mass in the continuous phase. If youare not using the non-premixed combustion model, DPM Mass Source will be equal to the sum of all speciesmass sources (DPM species-n Source, below); if you are using the non-premixed combustion model, it willbe equal to DPM Burnout plus DPM Evaporation/Devolatilization. The unit quantity for DPM Mass Sourceis mass-flow.

DPM Scattering(in the Discrete Phase Model... category) is the scattering coefficient for discrete-phase calculations that involve

radiation ( in

Its unit quantity is length-inverse.

DPM Sensible Enthalpy Source(in the Discrete Phase Model... category) is the exchange of sensible enthalpy from the discrete phase to thecontinuous phase. The exchange is positive when the particles are a source of heat in the continuous phase. Itsunit quantity is power.

DPM species-n Source(in the Discrete Phase Model... category) is the exchange of mass, due to droplet-particle evaporation orcombusting-particle devolatilization, from the discrete phase to the evaporating or devolatilizing species. (Thename of the species will replace species-n in DPM species-n Source.) These species are specified in the SetInjection Properties panel, as described in Defining Injection Properties. The unit quantity is mass-flow. Notethat this variable will not be available if you are using the non-premixed combustion model; use DPMEvaporation/Devolatilization instead.

DPM Swirl Momentum Source(in the Discrete Phase Model... category) is the exchange of swirl momentum from the discrete phase to thecontinuous phase. This value is positive when the particles are a source of momentum in the continuous phase.The unit quantity is force.

99



Variables D-J

DPM X, Y, Z Momentum Source(in the Discrete Phase Model... category) are the exchange of x-, y-, and x-direction momentum from thediscrete phase to the continuous phase. These values are positive when the particles are a source of momentumin the continuous phase. The unit quantity is force.

Dynamic Pressure(in the Pressure... category) is defined as

. Its unit quantity is pressure.

Eff Diff Coef of species-n(in the Species... category) is the sum of the laminar and turbulent diffusion coefficients of a species into themixture:

(The name of the species will replace species-n in Eff Diff Coef of species-n.) The unit quantity ismass-diffusivity.

Effective Prandtl Number

(in the Turbulence... category) is the ratio , where is the effective viscosity, is the

specific heat, and is the effective thermal conductivity.

Effective Thermal Conductivity

(in the Properties... category) is the sum of the laminar and turbulent thermal conductivities, , of the

fluid. A large thermal conductivity is associated with a good heat conductor and a small thermal conductivitywith a poor heat conductor (good insulator). Its unit quantity is thermal-conductivity.

Effective Viscosity

(in the Turbulence... category) is the sum of the laminar and turbulent viscosities of the fluid. Viscosity, ,

is defined by the ratio of shear stress to the rate of shear. Its unit quantity is viscosity.

Enthalpy(in the Temperature... category) is defined differently for compressible and incompressible flows, and dependingon the solver and models in use.

For compressible flows,

and for incompressible flows,

where and are, respectively, the mass fraction and enthalpy of species . (See Enthalpy of species-n,

below.) For the pressure-based solver, the second term on the right-hand side of



Variables D-J

is included only if the pressure work term is included in the energy equation (see Inclusion of Pressure Workand Kinetic Energy Terms in the ANSYS FLUENT documentation. For multiphase models, this value correspondsto the selected phase in the Phase drop-down list. For all species models, the Enthalpy plots consist of thethermal (or sensible) plus chemical energy. The unit quantity for Enthalpy is specific-energy.

Enthalpy of species-n(in the Species... category) is defined differently depending on the solver and models options in use. Thequantity:

where is the formation enthalpy of species at the reference temperature , is reported

only for non-diabatic PDF cases, or if the density-based solver is selected. The quantity:

where is reported in all other cases. The unit quantity for Enthalpy of species-n is

specific-energy.

Entropy(in the Temperature... category) is a thermodynamic property defined by the equation

where "rev" indicates an integration along a reversible path connecting two states, is heat, and is

temperature. For compressible flows, entropy is computed using the equation

where is computed from , and the reference pressure and density are defined in the ReferenceValues panel. For incompressible flow, the entropy is computed using the equation

where is the specific heat at constant pressure and is defined in the Reference Values panel. The

unit quantity for entropy is specific-heat.

Existing Value(in the Adaption... category) is the value that presently resides in the temporary space reserved for cell variables(that is, the last value that you displayed or computed).

Face Handedness(in the Grid... category) is a parameter that is equal to one in cells that are adjacent to left-handed faces, andzero elsewhere. It can be used to locate mesh problems.

101



Variables D-J

Face Squish Index(in the Grid... category) is a measure of the quality of a mesh, and is calculated from the dot products of eachface area vector, and the vector that connects the centroids of the two adjacent cells as

Therefore, the worst cells will have a Face Squish Index close to 1.

Fine Scale Mass Fraction of species-n

(in the Species... category) is the term in

Fine Scale Temperature(in the Temperature... category) is the temperature of the fine scales, which is calculated from the enthalpy

when the reaction proceeds over the time scale ( in

which is governed by the Arrhenius rates of

Its unit quantity is temperature.

Fine Scale Transfer Rate(in the Species... category) is the transfer rate of the fine scales, which is equal to the inverse of the time scale

( in

Its unit quantity is time-inverse.

1-Fine Scale Volume Fraction

(in the Species... category) is a function of the fine scale volume fraction ( in

where * denotes fine-scale quantities, is the volume fraction constant (= 2.1377), and is the kinematic

viscosity. The quantity is subtracted from unity to make it easier to interpret.



Variables D-J

Fvar Prod(in the Pdf... category) is the production term in the mixture fraction variance equation solved in the non-premixedcombustion model (that is, the last two terms in

Fvar2 Prod(in the Pdf... category) is the production term in the secondary mixture fraction variance equation solved in thenon-premixed combustion model.

Gas Constant (R)(in the Properties... category) is the gas constant of the fluid. Its unit quantity is specific-heat.

Granular Conductivity(in the Properties... category) is equivalent to the diffusion coefficient in

where:

• is the generation of energy by the solid stress tensor

• is the diffusion of energy ( is the diffusion coefficient)

• is the collisional dissipation of energy

• is the energy exchange between the lth fluid or solid phase and the s th solid phase.

For more information, see Granular Temperature in the ANSYS FLUENT documentation. Its unit quantity iskg/m-s.

Granular Pressure...

includes quantities for reporting the solids pressure for each granular phase ( in

See Solids Pressure in the ANSYS FLUENT documentation for details. Its unit quantity is pressure. Formultiphase models, this value corresponds to the selected phase in the Phase drop-down list.

Granular Temperature...

includes quantities for reporting the granular temperature for each granular phase, which is in

See Granular Temperature in the ANSYS FLUENT documentation for details. Its unit quantity is .

For multiphase models, this value corresponds to the selected phase in the Phase drop-down list.

Grid...includes variables related to the grid.

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Variables D-J

Grid X-Velocity, Grid Y-Velocity, Grid Z-Velocity(in the Velocity... category) are the vector components of the grid velocity for moving-grid problems (rotatingor multiple reference frames, mixing planes, or sliding meshes). Its unit quantity is velocity.

HCN Density(in the NOx... category) is the mass per unit volume of HCN. The unit quantity is density. The HCN Densitywill appear only if you are modeling fuel NOx. See Fuel NOx Formation in the ANSYS FLUENT documentationfor details.

Helicity(in the Velocity... category) is defined by the dot product of vorticity and the velocity vector.

It provides insight into the vorticity aligned with the fluid stream. Vorticity is a measure of the rotation of afluid element as it moves in the flow field.

Incident Radiation

(in the Radiation... category) is the total radiation energy, , that arrives at a location per unit time and perunit area:

where is the radiation intensity and is the solid angle. is the quantity that the P-1 radiation modelcomputes.

For the DO radiation model, the incident radiation is computed over a finite number of discrete solid angles,each associated with a vector direction. The unit quantity for Incident Radiation is heat-flux.

Incident Radiation (Band n)

(in the Radiation... category) is the radiation energy contained in the wavelength band for the non-grayDO radiation model. Its unit quantity is heat-flux.

Internal Energy(in the Temperature... category) is the summation of the kinetic and potential energies of the molecules of thesubstance per unit volume (and excludes chemical and nuclear energies). Internal Energy is defined as

. Its unit quantity is specific-energy.

Variables J-RJet Acoustic Power

(in the Acoustics... category) is the acoustic power for turbulent axisymmetric jets in

where and are the radial and angular coordinates of the receiver location, and is the directional

acoustic intensity per unit volume of a jet defined by




Variables J-R

Jet Acoustic Power Level (dB)(in the Acoustics... category) is the acoustic power for turbulent axisymmetric jets, reported in dB:

where is the reference acoustic power ( by default).


Lam Diff Coef of species-n

(in the Species... category) is the laminar diffusion coefficient of a species into the mixture, . Its unit

quantity is mass-diffusivity.

Laminar Flame Speed

(in the Premixed Combustion... category) is the propagation speed of laminar premixed flames in

where:

• = model constant

• = RMS (root-mean-square) velocity (m/s)

• = laminar flame speed (m/s)

• = molecular heat transfer coefficient of unburnt mixture (thermal diffusivity) (m^2/s)

• = turbulence length scale (m), computed from

where is the turbulence dissipation rate.

• = turbulence time scale (s)

• = chemical time scale (s)

Its unit quantity is velocity.

LEE Self-Noise X-Source, LEE Self-Noise Y-Source, LEE Self-Noise Z-Source(in the Acoustics... category ) are the self-noise source terms in the linearized Euler equation for the acousticvelocity component, which is

105



Variables J-R

where refers to the corresponding acoustic components, and the prime superscript refers to the turbulentcomponents.

The right side of the equation can be considered as effective source terms responsible for sound generation.Among them, the first three terms involving turbulence are the main contributors. The first two terms denoted

by are often referred to as "shear-noise" source terms, since they involve the mean shear. The third term

denoted by is often called the "self-noise" source term, for it involves turbulent velocity components

only.

The LEE self-noise variables are available only when the Broadband Noise Sources acoustics model is beingused.

LEE Shear-Noise X-Source, LEE Shear-Noise Y-Source, LEE Shear-Noise Z-Source(in the Acoustics... category ) are the shear-noise source terms in the linearized Euler equation for the acousticvelocity component, which is

The LEE shear-noise variables are available only when the Broadband Noise Sources acoustics model is beingused. (See LEE Self-Noise X-Source for details.)

LEE Total Noise X-Source, LEE Total Noise Y-Source, LEE Total Noise Z-Source(in the Acoustics... category ) are the total noise source terms in the linearized Euler equation for the acousticvelocity component, which is

The total noise source term is the sum of the self-noise and shear-noise source terms. They are available onlywhen the Broadband Noise Sources acoustics model is being used. (See LEE Self-Noise X-Source for details.)

Lilley's Self-Noise Source(in the Acoustics... category) is the self-noise source term in the linearized Lilley's equation, which is

Lilley's self-noise source term is available only when the Broadband Noise Sources acoustics model is beingused. The resulting source terms in the equation are evaluated using the mean velocity field and the turbulent(fluctuating) velocity components synthesized by the SNGR method. As with the LEE source terms, the sourceterms in the equation are grouped depending on whether the mean velocity gradients are involved (shear noiseor self noise), and reported separately in ANSYS FLUENT.

Lilley's Shear-Noise Source(in the Acoustics... category) is the shear-noise source term in the linearized Lilley's equation, which is



Variables J-R

Lilley's shear-noise source term is available only when the Broadband Noise Sources acoustics model is beingused. (See Lilley's Self-Noise X-Source for details.)

Lilley's Total Noise Source(in the Acoustics... category ) is the total noise source term in the linearized Lilley's equation, which is

The total noise source term is the sum of the self-noise and shear-noise source terms, and is available only whenthe Broadband Noise Sources acoustics model is being used. (See Lilley's Self-Noise X-Source for details.)

Liquid Fraction

(in the Solidification/Melting... category) the liquid fraction computed by the solidification/melting model:

Mach Number(in the Velocity... category) is the ratio of velocity and speed of sound.

Mass fraction of HCN, Mass fraction of NH3, Mass fraction of NO, Mass fraction of N2O(in the NOx... category) are the mass of HCN, the mass of NH3, the mass of NO, and the mass of N2O per unitmass of the mixture (for example, kg of HCN in 1 kg of the mixture). The Mass fraction of HCN and the Massfraction of NH3 will appear only if you are modeling fuel NOx. See Fuel NOx Formation in the ANSYSFLUENT documentation for details.

Mass fraction of nuclei(in the Soot... category) is the number of particles per unit mass of the mixture (in units of particles x10^15/kg.The Mass fraction of nuclei will appear only if you use the two-step soot model. See Soot Formation in theANSYS FLUENT documentation for details.

Mass fraction of soot(in the Soot... category) is the mass of soot per unit mass of the mixture (for example, kg of soot in 1 kg of themixture). See Soot Formation in the ANSYS FLUENT documentation for details.

Mass fraction of species-n(in the Species... category) is the mass of a species per unit mass of the mixture (for example, kg of species in1 kg of the mixture).

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Variables J-R

Mean quantity-n(in the Unsteady Statistics... category) is the time-averaged value of a solution variable (for example, StaticPressure). See Postprocessing for Time-Dependent Problems in the ANSYS FLUENT documentation fordetails.

Meridional Coordinate(in the Grid... category) is the normalized (dimensionless) coordinate that follows the flow path from inlet tooutlet. Its value varies from 0 to 1.

Mixture Fraction Variance(in the Pdf... category) is the variance of the mixture fraction solved for in the non-premixed combustion model.This is the second conservation equation (along with the mixture fraction equation) that the non-premixedcombustion model solves. (See Definition of the Mixture Fraction in the ANSYS FLUENT documentation.)

Modified Turbulent Viscosity

(in the Turbulence... category) is the transported quantity that is solved for in the Spalart-Allmaras turbulencemodel:

where is the production of turbulent viscosity and is the destruction of turbulent viscosity that occurs

in the near-wall region due to wall blocking and viscous damping. and are constants and $\nu$ is

the molecular kinematic viscosity. is a user-defined source term.

The turbulent viscosity, , is computed directly from this quantity using the relationship given by

where the viscous damping function, is given by

and

Its unit quantity is viscosity.

Molar Concentration of species-n(in the Species... category) is the moles per unit volume of a species. Its unit quantity is concentration.

Mole fraction of species-n(in the Species... category) is the number of moles of a species in one mole of the mixture.

Mole fraction of HCN, Mole fraction of NH3, Mole fraction of NO, Mole fraction of N2O(in the NOx... category) are the number of moles of HCN, NH3, NO, and N2O in one mole of the mixture. TheMole fraction of HCN and the Mole fraction of NH3 will appear only if you are modeling fuel NOx. SeeFuel NOx Formation in the ANSYS FLUENT documentation for details.

Mole fraction of soot(in the Soot... category) is the number of moles of soot in one mole of the mixture.



Variables J-R

Molecular Prandtl Number

(in the Properties... category) is the ratio .

Molecular Viscosity

(in the Properties... category) is the laminar viscosity of the fluid. Viscosity, , is defined by the ratio of shear

stress to the rate of shear. Its unit quantity is viscosity. For multiphase models, this value corresponds to theselected phase in the Phase drop-down list. For granular phases, this is equivalent to the solids shear viscosity

in

NH3 Density, NO Density, N2O Density(in the NOx... category) are the mass per unit volume of NH3, NO and N2O. The unit quantity for each isdensity. The NH3 Density will appear only if you are modeling fuel NOx. See Fuel NOx Formation in theANSYS FLUENT documentation for details.

NOx...contains quantities related to the NOx model. See NOx Formation in the ANSYS FLUENT documentation fordetails about this model.

Partition Boundary Cell Distance(in the Grid... category) is the smallest number of cells which must be traversed to reach the nearest partition(interface) boundary.

Partition Neighbors(in the Cell Info... category) is the number of adjacent partitions (that is, those that share at least one partitionboundary face (interface)). It gives a measure of the number of messages that will have to be generated forparallel processing.

Pdf...contains quantities related to the non-premixed combustion model, which is described in Modeling Non-PremixedCombustion in the ANSYS FLUENT documentation.

Phases...contains quantities for reporting the volume fraction of each phase. See Modeling Multiphase Flows in theANSYS FLUENT documentation for details.

Pitchwise Coordinate(in the Grid... category) is the normalized (dimensionless) coordinate in the circumferential (pitchwise) direction.Its value varies from 0 to 1.

Preconditioning Reference Velocity(in the Velocity... category) is the reference velocity used in the coupled solver's preconditioning algorithm.See Preconditioning in the ANSYS FLUENT documentation for details.

Premixed Combustion...contains quantities related to the premixed combustion model, which is described in Modeling PremixedCombustion in the ANSYS FLUENT documentation.

Pressure...includes quantities related to a normal force per unit area (the impact of the gas molecules on the surfaces ofa control volume).

Pressure Coefficient(in the Pressure... category) is a dimensionless parameter defined by the equation

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Variables J-R

where is the static pressure, is the reference pressure, and is the reference dynamic pressure

defined by . The reference pressure, density, and velocity are defined in the Reference Valuespanel.

Product Formation Rate

(in the Premixed Combustion... category) is the source term in the progress variable transport equation (

in

where = mean reaction progress variable, Sct = turbulent Schmidt number, and = reaction progress source

term (s^-1). Its unit quantity is time-inverse.

Production of k(in the Turbulence... category) is the rate of production of turbulence kinetic energy (times density). Its unitquantity is turb-kinetic-energy-production. For multiphase models, this value corresponds to the selectedphase in the Phase drop-down list.

Progress Variable

(in the Premixed Combustion... category) is a normalized mass fraction of the combustion products ( = 1)

or unburnt mixture products ( = 0), as defined by

where = number of products, = mass fraction of product species , = equilibrium mass fraction

of product species .

Properties...includes material property quantities for fluids and solids.

Variables RRate of NO

(in the NOx... category) is the overall rate of formation of NO due to all active NO formation pathways (forexample, thermal, prompt, etc.).

Rate of Nuclei(in the Soot... category) is the overall rate of formation of nuclei.

Rate of N2OPath NO(in the NOx... category) is the rate of formation of NO due to the N2O pathway only (available only when N2Opathway is active).

Rate of Prompt NO(in the NOx... category) is the rate of formation of NO due to the prompt pathway only (available only whenprompt pathway is active).

Rate of Reburn NO(in the NOx... category) is the rate of formation of NO due to the reburn pathway only (available only whenreburn pathway is active).



Variables R

Rate of SNCR NO(in the NOx... category) is the rate of formation of NO due to the SNCR pathway only (available only whenSNCR pathway is active).

Rate of Soot(in the Soot... category) is the overall rate of formation of soot mass.

Rate of Thermal NO(in the NOx... category) is the rate of formation of NO due to the thermal pathway only (available only whenthermal pathway is active).

Rate of Fuel NO(in the NOx... category) is the rate of formation of NO due to the fuel pathway only (available only when fuelpathway is active).

Rate of USER NO(in the NOx... category) is the rate of formation of NO due to user defined rates only (available only when UDFrates are added).

Radial Coordinate(in the Grid... category) is the length of the radius vector in the polar coordinate system. The radius vector isdefined by a line segment between the node and the axis of rotation. You can define the rotational axis in theFluid panel. See Velocity Reporting Options in the ANSYS FLUENT documentation. The unit quantity forRadial Coordinate is length.

Radial Pull Velocity(in the Solidification/Melting... category) is the radial-direction component of the pull velocity for the solidmaterial in a continuous casting process. Its unit quantity is velocity.

Radial Velocity(in the Velocity... category) is the component of velocity in the radial direction. (See Velocity Reporting Optionsin the ANSYS FLUENT documentation for details.) The unit quantity for Radial Velocity is velocity. Formultiphase models, this value corresponds to the selected phase in the Phase drop-down list.

Radial-Wall Shear Stress(in the Wall Fluxes... category) is the radial component of the force acting tangential to the surface due tofriction. Its unit quantity is pressure.

Radiation...includes quantities related to radiation heat transfer. See Modeling Radiation in the ANSYS FLUENTdocumentation.

Radiation Heat Flux(in the Wall Fluxes... category) is the rate of radiation heat transfer through the control surface. It is calculatedby the solver according to the specified radiation model. Heat flux out of the domain is negative, and heat fluxinto the domain is positive. The unit quantity for Radiation Heat Flux is heat-flux.

Radiation Temperature

(in the Radiation... category) is the quantity , defined by

where is the Incident Radiation. The unit quantity for Radiation Temperature is temperature.

Rate of Reaction-n(in the Reactions... category) is the effective rate of progress of the nth reaction. For the finite-rate model, thevalue is the same as the Arrhenius Rate of Reaction-n. For the eddy-dissipation model, the value is equivalentto the Turbulent Rate of Reaction-n. For the finite-rate/eddy-dissipation model, it is the lesser of the two.

Reactions...includes quantities related to finite-rate reactions. See Modeling Species Transport and Finite-Rate Chemistryin the ANSYS FLUENT documentation for information about modeling finite-rate reactions.

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Variables R

Reflected Radiation Flux (Band-n)(in the Wall Fluxes... category) is the amount of radiative heat flux reflected by a semi-transparent wall for aparticular band of radiation. Its unit quantity is heat-flux.

Reflected Visible Solar Flux, Reflected IR Solar Flux(in the Wall Fluxes... category) is the amount of solar heat flux reflected by a semi-transparent wall for a visibleor infrared (IR) radiation.

Refractive Index(in the Radiation... category) is a nondimensional parameter defined as the ratio of the speed of light in avacuum to that in a material. See Specular Semi-Transparent Walls in the ANSYS FLUENT documentationfor details.

Relative Axial Velocity(in the Velocity... category) is the axial-direction component of the velocity relative to the reference framemotion. See Velocity Reporting Options in the ANSYS FLUENT documentation for details. The unit quantityfor Relative Axial Velocity is velocity.

Relative Humidity(in the Species... category) is the ratio of the partial pressure of the water vapor actually present in an air-watermixture to the saturation pressure of water vapor at the mixture temperature. ANSYS FLUENT computes thesaturation pressure, , from the equation

where:

• = 22.089 MPa

• = 647.286 K

• = -7.4192420

• = 2.9721000 E10^-1

• = -1.1552860 E10^-1

• = 8.6856350 E10^-3

• = 1.0940980 E10^-3

• = -4.3999300 E10^-3

• = 2.5206580 E10^-3

• = -5.2186840 E10^-4

• = 0.01

• = 338.15 K

Relative Length Scale (DES)(in the Turbulence... category) is defined by



Variables R

where is an RANS-based length scale, and is an LES-based length scale. All of the cells

inside the domain in which belong to the LES region, and all of the cells inside the domain in which

belong to the RANS region.

Relative Mach Number(in the Velocity... category) is the nondimensional ratio of the relative velocity and speed of sound.

Relative Radial Velocity(in the Velocity... category) is the radial-direction component of the velocity relative to the reference framemotion. See Velocity Reporting Options in the ANSYS FLUENT documentation for details.) The unit quantityfor Relative Radial Velocity is velocity.

Relative Swirl Velocity(in the Velocity... category) is the tangential-direction component of the velocity relative to the reference framemotion, in an axisymmetric swirling flow. See Velocity Reporting Options in the ANSYS FLUENTdocumentation for details. The unit quantity for Relative Swirl Velocity is velocity.

Relative Tangential Velocity(in the Velocity... category) is the tangential-direction component of the velocity relative to the reference framemotion. (See Velocity Reporting Options in the ANSYS FLUENT documentation for details.) The unit quantityfor Relative Tangential Velocity is velocity.

Relative Total Pressure(in the Pressure... category) is the stagnation pressure computed using relative velocities instead of absolutevelocities; i.e., for incompressible flows the dynamic pressure would be computed using the relative velocities.(See Velocity Reporting Options in the ANSYS FLUENT documentation for more information about relativevelocities.) The unit quantity for Relative Total Pressure is pressure.

Relative Total Temperature(in the Temperature... category) is the stagnation temperature computed using relative velocities instead ofabsolute velocities. (See Velocity Reporting Options in the ANSYS FLUENT documentation for more informationabout relative velocities.) The unit quantity for Relative Total Temperature is temperature.

Relative Velocity Angle(in the Velocity... category) is similar to the Velocity Angle except that it uses the relative tangential velocity,and is defined as

Its unit quantity is angle.

Relative Velocity Magnitude(in the Velocity... category) is the magnitude of the relative velocity vector instead of the absolute velocity

vector. The relative velocity ( ) is the difference between the absolute velocity ( ) and the grid velocity.For simple rotation, the relative velocity is defined as

where is the angular velocity of a rotating reference frame about the origin and is the position vector.(See Velocity Reporting Options in the ANSYS FLUENT documentation.) The unit quantity for RelativeVelocity Magnitude is velocity.

Relative X Velocity, Relative Y Velocity, Relative Z Velocity(in the Velocity... category) are the x-, y-, and z-direction components of the velocity relative to the referenceframe motion. (See Velocity Reporting Options in the ANSYS FLUENT documentation for details.) The unitquantity for these variables is velocity.

Residuals...contains different quantities for the pressure-based and density-based solvers:

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Variables R

• In the density-based solvers, this category includes the corrections to the primitive variables pressure,velocity, temperature, and species, as well as the time rate of change of the corrections to these primitivevariables for the current iteration (i.e., residuals). Corrections are the changes in the variables between thecurrent and previous iterations and residuals are computed by dividing a cell's correction by its physicaltime step. The total residual for each variable is the summation of the Euler, viscous, and dissipationcontributions. The dissipation components are the vector components of the flux-like, face-based dissipationoperator.

• In the pressure-based solver, only the Mass Imbalance in each cell is reported (unless you have requestedothers, as described in Postprocessing Residual Values in the ANSYS FLUENT documentation. Atconvergence, this quantity should be small compared to the average mass flow rate.

RMS quantity-n(in the Unsteady Statistics... category) is the root mean squared value of a solution variable (for example,Static Pressure). See Postprocessing for Time-Dependent Problems in the ANSYS FLUENT documentationfor details.

Rothalpy(in the Temperature... category) is defined as

where is the enthalpy, is the relative velocity magnitude, and is the magnitude of the rotational

velocity .

Variables SScalar-n

(in the User Defined Scalars... category) is the value of the nth scalar quantity you have defined as a user-definedscalar. See the separate UDF manual for more information about user-defined scalars.

Scalar Dissipation(in the Pdf... category) is one of two parameters that describes the species mass fraction and temperature for alaminar flamelet in mixture fraction spaces. It is defined as

where is the mixture fraction and is a representative diffusion coefficient (see The Flamelet Concept in

the ANSYS FLUENT documentation for details). Its unit quantity is time-inverse.

Scattering Coefficient(in the Radiation... category) is the property of a medium that describes the amount of scattering of thermalradiation per unit path length for propagation in the medium. It can be interpreted as the inverse of the meanfree path that a photon will travel before undergoing scattering (if the scattering coefficient does not vary alongthe path). The unit quantity for Scattering Coefficient is length-inverse.

Secondary Mean Mixture Fraction(in the Pdf... category) is the mean ratio of the secondary stream mass fraction to the sum of the fuel, secondarystream, and oxidant mass fractions. It is the secondary-stream conserved scalar that is calculated by thenon-premixed combustion model. See Definition of the Mixture Fraction in the ANSYS FLUENT documentation.

Secondary Mixture Fraction Variance(in the Pdf... category) is the variance of the secondary stream mixture fraction that is solved for in thenon-premixed combustion model. See Definition of the Mixture Fraction in the ANSYS FLUENT documentation.

Sensible Enthalpy(in the Temperature... category) is available when any of the species models are active and displays only thethermal (sensible) enthalpy.



Variables S

Skin Friction Coefficient(in the Wall Fluxes... category) is a nondimensional parameter defined as the ratio of the wall shear stress andthe reference dynamic pressure

where is the wall shear stress, and and are the reference density and velocity defined in the

Reference Values panel. For multiphase models, this value corresponds to the selected phase in the Phasedrop-down list.

Solar Heat Flux(in the Wall Fluxes... category) is the rate of solar heat transfer through the control surface. Heat flux out ofthe domain is negative and heat flux into the domain is positive.

Solidification/Melting...contains quantities related to solidification and melting.

Soot...contains quantities related to the Soot model, which is described in Soot Formation in the ANSYS FLUENTdocumentation.

Soot Density(in the Soot... category) is the mass per unit volume of soot. The unit quantity is density. See Fuel NOxFormation in the ANSYS FLUENT documentation for details.

Sound Speed

(in the Properties... category) is the acoustic speed. It is computed from . Its unit quantity is velocity.

Spanwise Coordinate(in the Grid... category) is the normalized (dimensionless) coordinate in the spanwise direction, from hub tocasing. Its value varies from 0 to 1.

species-n Source Term(in the Species... category) is the source term in each of the species transport equations due to reactions. Theunit quantity is always kg/m^3-s.

Species...includes quantities related to species transport and reactions.

Specific Dissipation Rate (Omega)(in the Turbulence... category) is the rate of dissipation of turbulence kinetic energy in unit volume and time.Its unit quantity is time-inverse.

Specific Heat (Cp)(in the Properties... category) is the thermodynamic property of specific heat at constant pressure. It is definedas the rate of change of enthalpy with temperature while pressure is held constant. Its unit quantity isspecific-heat.

Specific Heat Ratio (gamma)(in the Properties... category) is the ratio of specific heat at constant pressure to the specific heat at constantvolume.

Stored Cell Partition(in the Cell Info... category) is an integer identifier designating the partition to which a particular cell belongs.In problems in which the grid is divided into multiple partitions to be solved on multiple processors using theparallel version of ANSYS FLUENT, the partition ID can be used to determine the extent of the various groupsof cells. The active cell partition is used for the current calculation, while the stored cell partition (the lastpartition performed) is used when you save a case file. See Partitioning the Grid Manually in the ANSYSFLUENT documentation for more information.

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Variables S

Static Pressure(in the Pressure... category) is the static pressure of the fluid. It is a gauge pressure expressed relative to theprescribed operating pressure. The absolute pressure is the sum of the Static Pressure and the operating pressure.Its unit quantity is pressure.

Static Temperature(in the Temperature... and Premixed Combustion... categories) is the temperature that is measured movingwith the fluid. Its unit quantity is temperature.

Note that Static Temperature will appear in the Premixed Combustion... category only for adiabatic premixedcombustion calculations. See Calculations in the ANSYS FLUENT documentation.

Strain Rate

(in the Derivatives... category) relates shear stress to the viscosity. Also called the shear rate ( in

), the strain rate is related to the second invariant of the rate-of-deformation tensor .

Its unit quantity is time-inverse. In 3D Cartesian coordinates, the strain rate, , is defined as

For multiphase models, this value corresponds to the selected phase in the Phase drop-down list.

Stream Function(in the Velocity... category) is formulated as a relation between the streamlines and the statement of conservationof mass. A streamline is a line that is tangent to the velocity vector of the flowing fluid. For a 2D planar flow,

the stream function, , is defined such that

where is constant along a streamline and the difference between constant values of stream function defining

two streamlines is the mass rate of flow between the streamlines.

The accuracy of the stream function calculation is determined by the text command/display/set/n-stream-func.

Stretch Factor(in the Premixed Combustion... category) is a nondimensional parameter that is defined as the probability of

unquenched flamelets, which is in

where erfc is the complementary error function, is the standard deviation of the distribution of :



Variables S

is the stretch factor coefficient for dissipation pulsation, is the turbulent integral length scale, and

is the Kolmogorov micro-scale. The default value of 0.26 for (measured in turbulent non-reacting flows)

is suitable for most premixed flames. is the turbulence dissipation rate at the critical rate of strain:

Subgrid Filter Length(in the Turbulence... category) is a mixing length for subgrid scales of the LES turbulence model, which is

defined as in

where is the von Kármán constant, is the distance to the closest wall, is the Smagorinsky constant,

and is the volume of the computational cell.

Lilly derived a value of 0.17 for for homogeneous isotropic turbulence in the inertial subrange. However,

this value was found to cause excessive damping of large-scale fluctuations in the presence of mean shear and

in transitional flows as near solid boundary, and has to be reduced in such regions. In short, is not an

universal constant, which is the most serious shortcoming of this simple model. Nonetheless, value of

around 0.1 has been found to yield the best results for a wide range of flows, and is the default value in ANSYSFLUENT.

Subgrid Kinetic Energy

(in the Turbulence... category) is the turbulence kinetic energy per unit mass of the unresolved eddies, ,

calculated using the LES turbulence model. It is defined as

Its unit quantity is turbulent-kinetic-energy.

Subgrid Turbulent Viscosity(in the Turbulence... category) is the turbulent (dynamic) viscosity of the fluid calculated using the LESturbulence model. It expresses the proportionality between the anisotropic part of the subgrid-scale stress tensorand the rate-of-strain tensor

where is the subgrid-scale turbulent viscosity. The isotropic part of the subgrid-scale stresses is not

modeled, but added to the filtered static pressure term. is the rate-of-strain tensor for the resolved scale

defined by


117



Variables S

Subgrid Turbulent Viscosity Ratio(in the Turbulence... category) is the ratio of the subgrid turbulent viscosity of the fluid to the laminar viscosity,calculated using the LES turbulence model.

Surface Acoustic Power(in the Acoustics... category) is the Acoustic Power per unit area generated by boundary layer turbulence

which can be interpreted as the local contribution per unit surface area of the body surface to the total acousticpower. The mean-square time derivative of the surface pressure and the correlation area are further approximatedin terms of turbulent quantities like turbulent kinetic energy, dissipation rate, and wall shear.

ANSYS FLUENT reports the acoustic surface power defined by the equation both in physical ( ) and

dB units.) It is available only when the Broadband Noise Sources acoustics model is being used. Its unitquantity is power per area.

Surface Acoustic Power Level (dB)(in the Acoustics... category) is the Acoustic Power per unit area generated by boundary layer turbulence, andrepresented in dB

as described in Surface Acoustic Power. It is available only when the Broadband Noise Sources acousticsmodel is being used.

Surface Cluster ID(in the Radiation... category) is used to view the distribution of surface clusters in the domain. Each clusterhas a unique integer number (ID) associated with it.

Surface Coverage of species-n(in the Species... category) is the amount of a surface species that is deposited on the substrate at a specificpoint in time.

Surface Deposition Rate of species-n(in the Species... category) is the amount of a surface species that is deposited on the substrate. Its unit quantityis mass-flux.

Surface dpdt RMS

(in the Acoustics... category) is the RMS value of the time-derivative of static pressure ( ). It is available

when the Ffowcs-Williams & Hawkings acoustics model is being used.

Surface Heat Transfer Coef.(in the Wall Fluxes... category), as defined in ANSYS FLUENT, is given by the equation

where is the combined convective and radiative heat flux, is the wall temperature, and is the

reference temperature defined in the Reference Values panel. Note that is a constant value that should

be representative of the problem. Its unit quantity is the heat-transfercoefficient.

Surface Incident Radiation(in the Wall Fluxes... category) is the net incoming radiation heat flux on a surface. Its unit quantity is heat-flux.



Variables S

Surface Nusselt Number(in the Wall Fluxes... category) is a local nondimensional coefficient of heat transfer defined by the equation

where is the heat transfer coefficient, is the reference length defined in the Reference Values

panel, and is the molecular thermal conductivity.

Surface Stanton Number(in the Wall Fluxes... category) is a nondimensional coefficient of heat transfer defined by the equation

where is the heat transfer coefficient, , and are reference values of density and velocity defined

in the Reference Values panel, and is the specific heat at constant pressure.

Swirl Pull Velocity(in the Solidification/Melting... category) is the tangential-direction component of the pull velocity for thesolid material in a continuous casting process. Its unit quantity is velocity.

Swirl Velocity(in the Velocity... category) is the tangential-direction component of the velocity in an axisymmetric swirlingflow. See Velocity Reporting Options in the ANSYS FLUENT documentation for details. The unit quantity forSwirl Velocity is velocity. For multiphase models, this value corresponds to the selected phase in the Phasedrop-down list.

Swirl-Wall Shear Stress(in the Wall Fluxes... category) is the swirl component of the force acting tangential to the surface due tofriction. Its unit quantity is pressure.

Variables T-ZTangential Velocity

(in the Velocity... category) is the velocity component in the tangential direction. (See Velocity ReportingOptions in the ANSYS FLUENT documentation for details.) The unit quantity for Tangential Velocity isvelocity.

Temperature...indicates the quantities associated with the thermodynamic temperature of a material.

Thermal Conductivity

(in the Properties... category) is a parameter ( ) that defines the conduction rate through a material via Fourier's

law ( ). A large thermal conductivity is associated with a good heat conductor and a small

thermal conductivity with a poor heat conductor (good insulator). Its unit quantity is thermal-conductivity.

Thermal Diff Coef of species-n

(in the Species... category) is the thermal diffusion coefficient for the nth species in these equations:

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Variables T-Z

where is the mass diffusion coefficient for species in the mixture and is the thermal (Soret)

diffusion coefficient. The equation above is strictly valid when the mixture composition is not changing, or

when is independent of composition. See the ANSYS FLUENT documentation for more information.

where is the effective Schmidt number for the turbulent flow:

and is the effective mass diffusion coefficient due to turbulence. See the ANSYS FLUENT documentation

for more information.

where is the mass fraction of species . See the ANSYS FLUENT documentation for more information.


Time Step

(in the Residuals... category) is the local time step of the cell, , at the current iteration level. Its unit quantityis time.

Time Step Scale(in the Species... category) is the factor by which the time step is reduced for the stiff chemistry solver (availablein the density-based solver only). The time step is scaled down based on an eigenvalue and positivity analysis.

Total Energy(in the Temperature... category) is the total energy per unit mass. Its unit quantity is specific-energy. For allspecies models, plots of Total Energy include the sensible, chemical and kinetic energies. For multiphasemodels, this value corresponds to the selected phase in the Phase drop-down list.

Total Enthalpy

(in the Temperature... category) is defined as where is the Enthalpy, as defined in

where is the mass fraction of species ), and is the velocity magnitude. Its unit quantity is

specific-energy. For all species models, plots of Total Enthalpy consist of the sensible, chemical and kineticenergies. For multiphase models, this value corresponds to the selected phase in the Phase drop-down list.

Total Enthalpy Deviation(in the Temperature... category) is the difference between Total Enthalpy and the reference enthalpy,

, where is the reference enthalpy defined in the Reference Values panel. However,

for non-premixed and partially premixed models, Total Enthalpy Deviation is the difference between TotalEnthalpy and total adiabatic enthalpy (total enthalpy where no heat loss or gain occurs). The unit quantity for



Variables T-Z

Total Enthalpy Deviation is specific-energy. For multiphase models, this value corresponds to the selectedphase in the Phase drop-down list.

Total Pressure(in the Pressure... category) is the pressure at the thermodynamic state that would exist if the fluid were broughtto zero velocity and zero potential. For compressible flows, the total pressure is computed using isentropic

relationships. For constant , this reduces to:

where is the static pressure, is the ratio of specific heats, and M is the Mach number. For incompressible

flows (constant density fluid), we use Bernoulli's equation, , where is the local

dynamic pressure. Its unit quantity is pressure.

Total Surface Heat Flux(in the Wall Fluxes... category) is the rate of total heat transfer through the control surface. It is calculated bythe solver according to the boundary conditions being applied at that surface. By definition, heat flux out ofthe domain is negative, and heat flux into the domain is positive. The unit quantity for Total Surface HeatFlux is heat-flux.

Total Temperature(in the Temperature... category) is the temperature at the thermodynamic state that would exist if the fluidwere brought to zero velocity. For compressible flows, the total temperature is computed from the total enthalpy

using the current method (specified in the Materials panel). For incompressible flows, the total temperature

is equal to the static temperature. The unit quantity for Total Temperature is temperature.

Transmitted Radiation Flux (Band-n)(in the Wall Fluxes... category) is the amount of radiative heat flux transmitted by a semi-transparent wall fora particular band of radiation. Its unit quantity is heat-flux.

Transmitted Visible Solar Flux, Transmitted IR Solar Flux(in the Wall Fluxes... category) is the amount of solar heat flux transmitted by a semi-transparent wall for avisible or infrared radiation.

Turbulence...includes quantities related to turbulence. See Modeling Turbulence in the ANSYS FLUENT documentation.

Turbulence Intensity(in the Turbulence... category) is the ratio of the magnitude of the RMS turbulent fluctuations to the referencevelocity:

where is the turbulence kinetic energy and is the reference velocity specified in the Reference Valuespanel. The reference value specified should be the mean velocity magnitude for the flow. Note that turbulenceintensity can be defined in different ways, so you may want to use a custom field function for its definition.See Custom Field Functions in the ANSYS FLUENT documentation for more information.

Turbulent Dissipation Rate (Epsilon)(in the Turbulence... category) is the turbulent dissipation rate. Its unit quantity is turbulent-energy-diss-rate.For multiphase models, this value corresponds to the selected phase in the Phase drop-down list.

Turbulent Flame Speed(in the Premixed Combustion... category) is the turbulent flame speed computed by ANSYS FLUENT using

=

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Variables T-Z

which is equal to

where

• = model constant

• = RMS (root-mean-square) velocity (m/s)

• = laminar flame speed (m/s)

• = molecular heat transfer coefficient of unburnt mixture (thermal diffusivity) (m^2/s)

• = turbulence length scale (m)

• = turbulence time scale (s)

• = chemical time scale (s)

(See Laminar Flame Speed for details.) Its unit quantity is velocity.

Turbulent Kinetic Energy (k)(in the Turbulence... category) is the turbulence kinetic energy per unit mass defined as

Its unit quantity is turbulent-kinetic-energy. For multiphase models, this value corresponds to the selectedphase in the Phase drop-down list.

Turbulent Rate of Reaction-n(in the Reactions... category) is the rate of progress of the nth reaction computed by

or

where:

• is the mass fraction of any product species,

• is the mass fraction of a particular reactant,

• is an empirical constant equal to 4.0

• is an empirical constant equal to 0.5



Variables T-Z

For the "eddy-dissipation" model, the value is the same as the Rate of Reaction-n. For the "finite-rate" model,the value is zero.

Turbulent Reynolds Number (Re_y)(in the Turbulence... category) is a nondimensional quantity defined as

where is turbulence kinetic energy, is the distance to the nearest wall, and is the laminar viscosity.

Turbulent Viscosity(in the Turbulence... category) is the turbulent viscosity of the fluid computed using the turbulence model. Itsunit quantity is viscosity. For multiphase models, this value corresponds to the selected phase in the Phasedrop-down list.

Turbulent Viscosity Ratio(in the Turbulence... category) is the ratio of turbulent viscosity to the laminar viscosity.

udm-n(in the User Defined Memory... category) is the value of the quantity in the nth user-defined memory location.

Unburnt Fuel Mass Fraction(in the Premixed Combustion... category) is the mass fraction of unburnt fuel. This function is available onlyfor non-adiabatic models.

Unsteady Statistics...includes mean and root mean square (RMS) values of solution variables derived from transient flow calculations.

User Defined Memory...includes quantities that have been allocated to a user-defined memory location. See the separate UDF Manualfor details about user-defined memory.

User-Defined Scalars...includes quantities related to user-defined scalars. See the separate UDF Manual for information about usinguser-defined scalars.

UU Reynolds Stress

(in the Turbulence... category) is the stress.

UV Reynolds Stress


UW Reynolds Stress


Variance of Species(in the NOx... category) is the variance of the mass fraction of a selected species in the flow field. It is calculatedfrom

where the constants , , and take the values 0.85, 2.86, and 2.0, respectively. See the ANSYS

FLUENT documentation for more information.

Variance of Species 1, Variance of Species 2(in the NOx... category) are the variances of the mass fractions of the selected species in the flow field. Theyare each calculated from the same equation as in Variance of Species.

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Variables T-Z

Variance of Temperature(in the NOx... category) is the variance of the normalized temperature in the flow field. It is calculated fromthe same equation as in Variance of Species.

Velocity...includes the quantities associated with the rate of change in position with time. The instantaneous velocity of

a particle is defined as the first derivative of the position vector with respect to time, , termed the

velocity vector, .

Velocity Angle(in the Velocity... category) is defined as follows:

For a 2D model,

For a 2D or axisymmetric model,

For a 3D model,

Its unit quantity is angle.

Velocity Magnitude(in the Velocity... category) is the speed of the fluid. Its unit quantity is velocity. For multiphase models, thisvalue corresponds to the selected phase in the Phase drop-down list.

Volume fraction(in the Phases... category) is the volume fraction of the selected phase in the Phase drop-down list.

Vorticity Magnitude(in the Velocity... category) is the magnitude of the vorticity vector. Vorticity is a measure of the rotation of afluid element as it moves in the flow field, and is defined as the curl of the velocity vector:

VV Reynolds Stress


VW Reynolds Stress


Wall Fluxes...includes quantities related to forces and heat transfer at wall surfaces.

Wall Func. Heat Tran. Coef.is defined by the equation



Variables T-Z

where is the specific heat, is the turbulence kinetic energy at point , and is defined in

See the ANSYS FLUENT documentation for more information.

Wall Shear Stress(in the Wall Fluxes... category) is the force acting tangential to the surface due to friction. Its unit quantity ispressure. For multiphase models, this value corresponds to the selected phase in the Phase drop-down list.

Wall Temperature (Inner Surface)(in the Temperature... category) is the temperature on the inner surface of a wall (corresponding to the sideof the wall surface away from the adjacent fluid or solid cell zone). Note that wall thermal boundary conditionsare applied on this surface:

The unit quantity for Wall Temperature (Inner Surface) is temperature.

Wall Temperature (Outer Surface)(in the Temperature... category) is the temperature on the outer surface of a wall (corresponding to the sideof the wall surface toward the adjacent fluid or solid cell zone). Note that wall thermal boundary conditionsare applied on the Inner Surface:

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Variables T-Z

The unit quantity for Wall Temperature (Outer Surface) is temperature.

Wall Yplus(in the Turbulence... category) is a nondimensional parameter defined by the equation

where is the friction velocity, is the distance from point to the wall, is the fluid

density, and is the fluid viscosity at point . See Near-Wall Treatments for Wall-Bounded Turbulent Flows

in the ANSYS FLUENT documentation for details. For multiphase models, this value corresponds to theselected phase in the Phase drop-down list.

Wall Ystar(in the Turbulence... category) is a nondimensional parameter defined by the equation

where is the turbulence kinetic energy at point , is the distance from point to the wall, is

the fluid density, and is the fluid viscosity at point . See Near-Wall Treatments for Wall-BoundedTurbulent Flows in the ANSYS FLUENT documentation for details.

WW Reynolds Stress


X-Coordinate, Y-Coordinate, Z-Coordinate(in the Grid... category) are the Cartesian coordinates in the x-axis, y-axis, and z-axis directions respectively.The unit quantity for these variables is length.

X Face Area, Y Face Area, Z Face Area(in the Grid... category) are the components of the boundary face area vectors stored in the adjacent boundarycells. The face area calculations are done as in X Surface Area, Y Surface Area, Z Surface Area (see below),



Variables T-Z

except the area values in the cells with more than one boundary face are not summed to obtain the cell values.Instead, the area value relative to the last visited face of each cell is taken as the cell value.

The face area calculation can be restricted to a set of zones. Your zone selection can be made from the BoundaryZones list contained in the Boundary Adaption panel. The face areas will be calculated only on the zonesselected, and in order to make your selection active, you need to click the Mark button in the BoundaryAdaption panel. Note that if the Boundary Zones list is empty, all boundary zones will be used.

X Pull Velocity, Y Pull Velocity, Z Pull Velocity(in the Solidification/Melting... category) are the x, y, and z components of the pull velocity for the solidmaterial in a continuous casting process. The unit quantity for each is velocity.

X Surface Area, Y Surface Area, Z Surface Area(in the Grid... category) are the components of the boundary face area vectors stored in the adjacent boundarycells. The surface area is accumulated from all boundary faces adjacent to the boundary cell. For each boundaryface zone, the component of the face area in the relevant direction (x, y, or z) is added to the cell value of theadjacent cell. For those cells having more than one boundary face, the cell value is the sum (accumulation) ofall the boundary face area values. In most circumstances, the X Surface Area, Y Surface Area, Z SurfaceArea are used for flux and surface integration. In the few instances where area accumulation must be avoided,you can mark the zones of interest and use X Face Area, Y Face Area, Z Face Area (see above) for flux andintegral calculations.

X Velocity, Y Velocity, Z Velocity(in the Velocity... category) are the components of the velocity vector in the x-axis, y-axis, and z-axis directions,respectively. The unit quantity for these variables is velocity. For multiphase models, these values correspondto the selected phase in the Phase drop-down list.

X-Vorticity, Y-Vorticity, Z-Vorticity(in the Velocity... category) are the x, y, and z components of the vorticity vector.

X-Wall Shear Stress, Y-Wall Shear Stress, Z-Wall Shear Stress(in the Wall Fluxes... category) are the x, y, and z components of the force acting tangential to the surface dueto friction. The unit quantity for these variables is pressure. For multiphase models, these values correspondto the selected phase in the Phase drop-down list.

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Variables T-Z

Chapter 7. Command ActionsYou can use command actions to edit or create graphic objects and to perform some typical actions (such as readingor creating session and state files). This chapter describes:

• Overview of Command Actions (p. 129)

• File Operations from the Command Editor Dialog Box (p. 130)

• Quantitative Calculations in the Command Editor Dialog Box (p. 136)

• Other Commands (p. 136)

Overview of Command ActionsAction statements are used to force CFD-Post to undertake a specific task, usually related to the input and outputof data from the system. You can use action statements in a variety of areas:

• You can enter command action statements into the Tools > Command Editor dialog box. All such actions mustbe preceded with the > symbol.

For details on the Command Editor dialog box, see Command Editor (p. 226). Additional information onediting and creating graphics objects using the CFX Command Language in the Command Editor dialog boxis available in CFX Command Language (CCL) in CFD-Post (p. 257).

• Command actions also appear in session files (where they are also preceded by the > character).

• When running CFD-Post in Line Interface mode, the CFX> command prompt is shown in a DOS window orUNIX shell. All the actions described in this section along with some additional commands can be entered atthe command prompt. You do not have to precede commands with the > symbol when running in Line Interfacemode. Additional information on using Line Interface mode is available in Line Interface Mode (p. 151).

NoteIn addition to command action statements, CCL takes advantage of the full range of capabilities andresources from an existing programming language, Perl. Perl statements can be embedded in betweenlines of simple syntax, providing capabilities such as loops, logic, and much, much more with any CCLinput file. These Power Syntax commands are preceded by the ! symbol. Additional information onusing Power Syntax in the Command Editor dialog box is available in Power Syntax in ANSYSCFX (p. 137).

Many actions require additional information to perform their task (such as the name of a file to load or the type offile to create). By default, these actions get the necessary information from a specific associated CCL singletonobject. For convenience, some actions accept a few arguments that are used to optionally override the commonlychanged object settings. If multiple arguments for an action are specified, they must be separated by a comma (,).Lines starting with the # character are not interpreted and can be used for comments.

For example, all the settings for >print are read from the HARDCOPY: object. However, if you desire, you canspecify the name of the hardcopy file as an argument to >print. The following CCL example demonstrates thisbehavior of actions:

# Define settings for printingHARDCOPY: Hardcopy Format= jpg Hardcopy Filename = default.jpg Image Scale = 70 White Background = OffEND#Create an output file based on the settings in HARDCOPY>print

129



#Create an identical output file with a different filename.>print another_file.jpg

File Operations from the Command Editor DialogBox

This section discusses the following topics:

• Loading a Results File (p. 130)

• Reading Session Files (p. 130)

• Saving State Files (p. 131)

• Reading State Files (p. 132)

• Creating a Hardcopy (p. 134)

• Importing External File Formats (p. 134)

• Exporting Data (p. 134)

• Viewer Controls (p. 135)

Loading a Results FileYou load a results file by using the >load command. The parameter settings for loading the file are read from theDATA READER object. For simplicity, some parameters may be set via optional parameters as part of the loadcommand.

>load [filename=<filename>][timestep=<timestep>]

If a timestep is not specified, a value of -1 is assumed (this corresponds to the Final state).

When a results file is loaded, all Domain, Boundary, and Variable objects associated with the results file arecreated or updated. Variable objects are created, but the associated data is not actually read into the post-processoruntil the variables are used (load-on-demand). Variables will be pre-loaded if specified in the DATA READER.

load Command ExamplesThe following are example >load commands with the expected results.

>load filename=c:/CFX/tutorials/Buoyancy2DVMI_002.res, timestep=3

This command loads the specified results file at timestep 3.

TipIf going from a transient to steady state results file, you should specify the timestep to be -1 (if this isnot the current setting). If you do not explicitly set this, you will get a warning message stating that theexisting timestep does not exist. The -1 timestep will then be loaded.

>load timestep=4

This command loads timestep 4 in the existing results file.

Reading Session Files>readsession [filename=<filename>]

The >readsession command performs session file reading and executing. The following option is available:

• filename = <filename>



File Operations from the Command Editor Dialog Box

This option specifies the filename and path to the file that should be read and executed. If no filename is specified,the SESSION singleton object indicates the file to use. If no SESSION singleton exists, an error will be raisedindicating that a filename must be specified.

readsession Command ExamplesThe following are example >readsession commands, and the expected results. If a SESSION singleton exists,the values of the parameters listed after the session command replaces the values stored in the SESSION singletonobject. For this command, the filename command parameter value replaces the session filename parametervalue in the SESSION singleton.

> readsession

This command reads the session file specified in the SESSION singleton, and execute its contents. If the SESSIONobject does not exist, an error will be raised indicating that a filename must be specified.

> readsession filename=mysession.cse

This command reads and execute the contents of the mysession.cse file.

Saving State Files>savestate [mode=<none | overwrite>][filename=<filename>]

State files can be used to quickly load a previous state into CFD-Post. State files can be generated manually usinga text editor, or from within CFD-Post by saving a state file. The commands required to save to these files from theCommand Editor dialog box are described below.

The >savestate command is used to write the current CFD-Post state to a file. The >savestate action supportsthe following options:

• mode = <none | overwrite>

If mode is none, the executor creates a new state file, and if the specified file exists, an error will be raised. Ifmode is overwrite, the executor creates a new state file, and if the file exists, it will be deleted and replacedwith the latest state information.


Specifies the path and name of the file that the state is to be written to. If no filename is specified, the STATEsingleton object will be queried for the filename. If the STATE singleton does not exist, then an error will beraised indicating that a filename must be specified.

savestate Command ExamplesThe following are example >savestate commands, and the expected results. If a STATE singleton exists, thevalues of the parameters listed after the >savestate command replaces the values stored in the STATE singletonobject. For this command, the filename command parameter value replaces the state filename parametervalue in the STATE singleton, and the mode command parameter value replaces the savestate mode parametervalue in the STATE singleton.

> savestate

This command writes the current state information to the filename specified in the STATE singleton. If the modein the STATE singleton is none, and the filename exists, an error will be returned. If the mode in the STATEsingleton is overwrite, and the filename exists, the existing file will be deleted, and the state information willbe written to the file. If the STATE singleton does not exist, an error will be raised indicating that a filename needsto be specified.

131



Saving State Files

> savestate mode=none

This command writes the current state information to the file specified in the STATE singleton. If the file alreadyexists, an error will be raised. If the STATE singleton does not exist, an error will be raised indicating that a filenameneeds to be specified.

> savestate mode=overwrite

This command writes the current state information to the file specified in the STATE singleton. If the file alreadyexists, it will be deleted, and the current state information will be saved in its place. If the STATE singleton doesnot exist, an error will be raised indicating that a filename needs to be specified.

> savestate filename=mystate.cst

This command writes the current state information to the mystate.cst file. If the STATE singleton exists, andthe savestate mode is set to none, and the file already exists, the command causes an error. If the savestatemode is set to overwrite, and the file already exists, the file will be deleted, and the current state informationwill be saved in its place. If the STATE singleton does not exist, then the system assumes a savestate modeof none, and behave as described above.

> savestate mode=none, filename=mystate.cst

This command writes the current state information to the mystate.cst file. If the file already exists, the commandcauses an error.

> savestate mode=overwrite, filename=mystate.cst

This command writes the current state information to the mystate.cst file. If the file already exists, it will bedeleted, and the current state information will be saved in its place.

Reading State Files>readstate [mode=<overwrite | append>][filename=<filename>, load=<true | false>]

The >readstate command loads an CFD-Post state from a specified file.

If a DATA READER singleton has been stored in the state file, the load action will be invoked to load the contentsof the results file.

If a state file contains BOUNDARY objects, and the state file is appended to the current state (with no new DATAREADER object), some boundaries defined may not be valid for the loaded results. BOUNDARY objects that are notvalid for the currently loaded results file will be culled.

>readstate supports the following options:

• mode = <overwrite | append>

If mode is set to overwrite, the executor deletes all the objects that currently exist in the system, and loadthe objects saved in the state file. Overwrite mode is the default mode if none is explicitly specified. If mode isset to append, the executor adds the objects saved in the state file to the objects that already exist in the system.If the mode is set to append and the state file contains objects that already exist in the system, the followinglogic will determine the final result:

If the system has an equivalent object (the name and type), then the object already in the system will be modifiedwith the parameters saved in the state file. If the system has an equivalent object in name only, then the objectthat already exists in the system will be deleted, and replaced with that in the state file.


The path to the state file.

• load = <true | false>



Reading State Files

If load is set to true and a DATA READER object is defined in the state file, then the results file will be loadedwhen the state file is read. If load is set to false, the results file will not be loaded, and the DATA READERobject that currently is in the object database (if any) will not be updated.

readstate Option ActionsThe following table describes the options, and what will happen based on the combination of options that are selected.

What happens tothe Data Reader

What happens to the objects?Load DataSelection

Mode Selection

It gets deleted andreplaced.

All user objects (planes, etc.) get deleted. The loading of thenew results file changes the default objects (boundaries,wireframe, etc.) including deletion of objects that are no

TrueOverwrite

longer relevant to the new results. Default objects that arenot explicitly modified by object definitions in the state filewill have all user modifiable values reset to default values.

If it exists, itremains unchanged

All user objects get deleted. All default objects that exist inthe state file updates the same objects in the current system

FalseOverwrite

regardless of whatis in the state file.

state if they exist. Default objects in the state file that do notexist in the current state will not be created. All user objectsin the state file will be created.

It is modified withnew value from thestate file.

No objects are initially deleted. The default objects in thestate file replaces the existing default objects. User objectswill:

TrueAppend

• Be created if they have a unique name.

• Replace existing objects if they have the same name butdifferent type.

• Update existing objects if they have the same name andtype.

If it exists, itremains unchanged

No objects are initially deleted. Default objects in the statefile will only overwrite those in the system if they already

FalseAppend

regardless of whatis in the state file.

exist. User objects have the same behavior as theAppend/True option above.

readstate Command ExamplesThe following are example >readstate commands, and the expected results. If a STATE singleton exists, thevalues of the parameters listed after the >readstate command replaces the values stored in the STATE singletonobject. For this command, the filename command parameter value replaces the state filename parametervalue in the STATE singleton, and the mode command parameter value replaces the readstate mode parametervalue in the STATE singleton.

> readstate filename=mystate.cst

The readstate mode parameter in the STATE singleton determines if the current objects in the system aredeleted before the objects defined in the mystate.cst file are loaded into the system. If the STATE singletondoes not exist, then the system objects are deleted before loading the new state information.

> readstate mode=overwrite, filename=mystate.cst

This command deletes all objects currently in the system, open the mystate.cst file if it exists, and create theobjects as stored in the state file.

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Reading State Files

> readstate mode=append, filename=mystate.cst

This command opens the mystate.cst file if it exists, and adds the objects defined in the file to those alreadyin the system following the rules specified in the previous table.

> readstate

This command overwrites or appends to the objects in the system using the objects defined in the file referencedby the state filename parameter in the STATE singleton. If the STATE singleton does not exist, an error willbe raised indicating that a filename must be specified.

> readstate mode=overwrite

This command overwrites the objects in the system STATE the objects defined in the file referenced by the statefilename parameter in the STATE singleton. If the STATE singleton does not exist, an error will be raisedindicating that a filename must be specified.

> readstate mode=append

This command appends to the objects in the system using the objects defined in the file referenced by the statefilename parameter in the STATE singleton. If the STATE singleton does not exist, an error will be raisedindicating that a filename must be specified.

Creating a Hardcopy>print [<filename>]

The >print command creates a file of the current viewer contents. Settings for output format, quality, etc. areread from the HARDCOPY singleton object.

The optional argument <filename> can be used to specify the name of the output file to override that stored inHARDCOPY. HARDCOPY must exist before print is executed.

Importing External File FormatsData import is controlled using the >import command. There are two file types that can be imported: ANSYS(*.cdb) and Generic (*.csv). The CCL options associated with the >import command are:

>import type=<Ansys | Generic>, filename=<filename>, object name=<name of object>, boundary=<associated boundary>, conserve flux=<true | false>

type - Indicates whether to import the file as an Ansys file or Generic file.

filename - The name of the file to import.

object name - the name to give the USER SURFACE object that is created as a result of importing the file.

boundary - the name of the CFD-Post boundary/region to associate with the imported ANSYS surface. Thisassociation is used during an ANSYS file import to project data from the ANSYS surface onto the CFD-Postboundary/region. The same association is used during an ANSYS file export, when data from the CFD-Postboundary/region is projected back onto the ANSYS surface.

conserve flux - boolean to indicate whether or not to ensure that the heat fluxes associated with the importedANSYS geometry remain conservative relative to the fluxes on the associated CFD-Post Boundary.

Exporting DataData export is controlled using the >export command. The names of variables to export, locations to export,filenames, etc., are defined in the EXPORT singleton object.



Creating a Hardcopy

Viewer ControlsThis section describes how multiple viewports can be accessed using Command Language, and how they are orderedand named.

The first (top-left) viewport is represented by the VIEWER singleton, while others are VIEWPORT objects. Forexample, to modify filtering in the first viewport, changes should be made to the VIEWER singleton. For all otherviewports, changes are made to the VIEWPORT objects, which are numbered from 1-3 in a clockwise direction.

For example, to filter the top-left viewport:

VIEWER Draw All Objects=false Object Name List=WireframeEND

To filter the bottom-right viewport when all four viewports are active:

VIEWPORT:Viewport 2 Draw All Objects=false Object Name List=WireframeEND

The following are examples of viewport layouts:

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Viewer Controls

Quantitative Calculations in the Command EditorDialog Box

When executing a calculation from the Command Editor dialog box, the result is displayed in the CalculatorWindow.

The >calculate command is used to perform function calculations in the Command Editor dialog box. Typing>calculate alone performs the calculation using the parameters stored in the CALCULATOR singleton object.Entering >calculate <function name> will not work if required arguments are needed by the function.

Other CommandsThe following topics will be discussed:

• Deleting Objects (p. 136)

• Viewing a Chart (p. 136)

• Turbo Post CCL Command Actions (p. 136)

Deleting Objects>delete <objectnamelist>

The >delete command can be used in the Command Editor dialog box to delete objects. The command mustbe supplied with a list of object names separated by commas. An error message will be displayed if the list containsany invalid object names, but the deletion of valid objects in the list will still be processed.

Viewing a Chart>chart <objectname>

The >chart command is used to invoke the Chart Viewer and display the specified Chart object. Chart objectsand Chart Lines are created like other CCL objects.

Turbo Post CCL Command Actions

Calculating Velocity Components

>turbo more vars

Issuing the >turbo more vars command is equivalent to selecting the Calculate Velocity Componentsin the Turbo workspace. For details, see Calculate Velocity Components (p. 248).

Initializing all Turbo Components

>turbo init

Issuing the >turbo init command is equivalent to selecting Initialize All Components from the Turbo menu.For details, see Initialize All Components (p. 231).



Quantitative Calculations in the Command Editor Dialog Box

Chapter 8. Power Syntax in ANSYS CFXProgramming constructs can be used within CCL for advanced usage. Rather than invent a new language, CCLtakes advantage of the full range of capabilities and resources from an existing programming language, Perl. Perlstatements can be embedded in between lines of simple syntax, providing capabilities such as loops, logic, andmuch, much more with any CCL input file.

Lines of Power Syntax are identified in a CCL file by an exclamation mark (!) at the start of each line. In betweenPerl lines, simple syntax lines may refer to Perl variables and lists.

A wide range of additional functionality is made available to expert users with the use of Power Syntax including:

• Loops

• Logic and control structures

• Lists and arrays

• Subroutines with argument handling (useful for defining commonly re-used plots and procedures)

• Basic I/O processing

• System functions

• Many other procedures (Object programming, World Wide Web access, simple embedded GUIs).

Any of the above may be included in a CCL input file or CFD-Post Session file.

ImportantYou should be wary when entering certain expressions because Power Syntax uses Perl mathematical

operators. For example, in CEL, 22 is represented as 2^2, but in Perl, it would be written 2**2. If youare unsure about the validity of an operator, you should check a Perl reference guide.

There are many good reference books on Perl. Two examples are “Learning Perl” (ISBN 1-56592-042-2)and “Programming Perl” (ISBN 1-56592-149-6) from the O'Reilly series.

This chapter describes:

• Examples of Power Syntax (p. 137)

• Predefined Power Syntax Subroutines (p. 140)

Examples of Power SyntaxThe following are some examples in which the versatility of power syntax is demonstrated. They become steadilymore complex in the later examples.

Some additional, more complex, examples of Power Syntax subroutines can be found by viewing the session filesused for the Macro Calculator. These are located in CFX/etc/. You can execute these subroutines from theCommand Editor dialog box the same as calling any other Power Syntax subroutine. The required argument formatis:

!cpPolar(<"BoundaryList">, <"SliceNormalAxis">, <"SlicePosition">, <"PlotAxis">, <"InletLocation">, <"ReferencePressure">)!compressorPerform(<"InletLocation">, <"OutletLocation">, <"BladeLocation">, <"MachineAxis">, <"RotationalSpeed">, <"TipRadius">, <"NumBlades">, <"FluidGamma">)

These subroutines are loaded when CFD-Post is launched, so you do not need to execute the session files beforeusing the functions.

Additional information on these macro functions is available. For details, see Gas Compressor Performance Macro(p. 212) and Cp Polar Plot Macro (p. 212).

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All arguments passed to subroutines should be enclosed in quotations, for example Plane 1 must be passed as“Plane 1” and Eddy Viscosity should be entered as “Eddy Viscosity”. Any legal CFX CommandLanguage characters that are illegal in Perl need to be enclosed in quotation marks.

Example 1: Print the Value of the Pressure Drop Through aPipe

! $Pin = massFlowAve("Pressure","inlet");! $Pout = massFlowAve("Pressure","outlet");! $dp = $Pin-$Pout;! print "The pressure drop is $dp\n";

Example 2: Using a for LoopThis example demonstrates using Power Syntax that wraps a for loop around some CCL Object definitions torepetitively change the visibility on the outer boundaries.

# Make the outer boundaries gradually transparent in# the specified number of steps.!$numsteps = 10;!for ($i=0; $i < $numsteps; $i++) { ! $trans = ($i+1)/$numsteps; BOUNDARY:in Visibility = 1 Transparency = $trans END BOUNDARY:out Visibility = 1 Transparency = $trans END BOUNDARY:Default Visibility = 1 Transparency = $trans END!}

The first line of Power Syntax simply defines a scalar variable called numsteps. Scalar variables (that is, simplesingle-valued variables) begin with a $ symbol in Perl. The next line defines a for loop that increments the variablei up to numsteps. Next, you determine the fraction you are along in the loop and assign it to the variable trans.The object definitions then use trans to set their transparency and then repeat. Note how Perl variables can bedirectly embedded into the object definitions. The final line of Power Syntax (!}) closes the for loop.



Example 1: Print the Value of the Pressure Drop Through a Pipe

Example 3: Creating a Simple SubroutineThe following example defines a simple subroutine to make two planes at specified locations. The subroutine willbe used in the next example.

!sub makePlanes { PLANE:plane1 Option = Point and Normal Point = 0.09,0,-0.03 Normal = 1,0,0 Draw Lines = On Line Color = 1,0,0 Color Mode = Variable Color Variable = Pressure Range = Local END PLANE:plane2 Option = Point and Normal Point = 0.08,-0.038,-0.0474 Normal = 1,0,0 Draw Faces = Off Draw Lines = On Line Color = 0,1,0 END!}

Although this subroutine is designed for use with the next example, you can execute it on its own by typing!makePlanes(); in the Command Editor dialog box.

Example 4: Creating a Complex Quantitative SubroutineThis example is a complex quantitative subroutine that takes slices through the manifold geometry, as shown below,compares the mass flow through the two sides of the initial branch, and computes the pressure drop through to thefour exit locations.

! sub manifoldCalcs{# call the previously defined subroutine (Example 3) make the# upstream and downstream cutting planes

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Example 3: Creating a Simple Subroutine

! makePlanes();## Bound the two planes so they each just cut one side of the branch.PLANE:plane1Plane Bound = CircularBound Radius = 0.025ENDPLANE:plane2Plane Bound = CircularBound Radius = 0.025END# Calculate mass flow through each using the predefined# 'evaluate' Power Syntax subroutine and output the results! ($mass1, $mfunits) = evaluate( "massFlow()\@plane1" );! ($mass2) = evaluate( "massFlow()\@plane2" );! $sum = $mass1+$mass2;! print "Mass flow through branch 1 = $mass1 [$mfunits]\n";! print "Mass flow through branch 2 = $mass2 [$mfunits]\n";! print "Total = $sum [$mfunits]\n";# Now calculate pressure drops and mass flows through the exits# calculate the average pressure at the inlet!($Pin, $punits) = evaluate( "massFlowAve(Pressure)\@in1" );# Set-up an array that holds the approximate X location of each# of the 4 exits. We then loop over the array to move the outlet# plane and re-do the pressure drop calculation at each exit.! @Xlocs = (0.15,0.25,0.35,0.45);! $sum = 0;! for ($i=0;$i<4;$i++) {PLANE:outlet Option = Point and Normal Normal = 0,-1,-1 Point = $Xlocs[$i],-0.06,-0.2 Plane Bound = Circular Bound Radius = 0.05END! ($Pout, $punits) = evaluate( "massFlowAve(Pressure)\@outlet" );! ($massFl) = evaluate( "massFlow()\@outlet" );! $sum += $massFl;! $Dp = $Pin-$Pout;! $ii = $i+1;! print "At outlet \#$ii: Dp = $Dp [$punits], Mass Flow = $massFl [$mfunits]\n";! } # end loop! print "Total Mass Flow = $sum [$mfunits]\n";!} # end subroutine

After processing these commands to define the subroutine, you can execute it, in the same way as any other subroutine,by typing !manifoldCalcs(); in the Command Editor dialog box.

Predefined Power Syntax SubroutinesCFD-Post provides predefined subroutines that add Power Syntax functionality. You can view a list of thesesubroutines by entering !showSubs(); in the Command Editor dialog box. The list is printed to the consolewindow. The list shows all currently loaded subroutines, so it will include any custom subroutines that you haveprocessed in the Command Editor dialog box.

These subroutines provide access to the quantitative functionality of CFD-Post. Most of these routines provideresults in a single return value. For example, if the Perl variable $verbose = 1, then the result is also printed to



Predefined Power Syntax Subroutines

the screen. Information on the calculations performed by the subroutines is available. For details, see FunctionSelection (p. 210).

The following sections describe these predefined subroutines:

• Subroutine Descriptions (p. 141)

• Usage (p. 141)

• Power Syntax Subroutines (p. 141)

Subroutine DescriptionsIn the next section, each subroutine will appear in the following format:

Each of the subroutines contains an argument list (in brackets, separated by commas). If any argument containsmore than one word (for example, Plane 1), it must be within quotes. You should enclose all arguments withinquotes to avoid making possible syntax errors.

Each subroutine is preceded by its return value(s). For example:

real, string evaluate("Expression, "Locator")

will return two values, a real number and a string.

The return values will always be in the solution units of the CFX-Solver results file, even if you have changed thedisplay units in the Edit menu. This means that if you have a plot of temperature in degrees C on Plane 1, thearea averaged value of temperature on Plane 1 returned by the areaAve command will still be in degrees K.

UsageAll lines of power syntax must have an exclamation mark as the first character so that they are not treated as CCLstatements. The statements must also end with a semi-colon. The following is an example:

! $lengthVal = Length("Plane 1");! print $lengthVal;

Some subroutines return more than one value. To store return values for a subroutine that returns two variables(such as the evaluate function), you could use the following:

! ($value, $units) = evaluate("Expression 1");! print "The value of Expression 1 is $value, and the units are $units";

Power Syntax Subroutines

area(Location,Axis)

real area("Location", "Axis")

Returns the value of area. For details, see area (p. 30).

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Subroutine Descriptions

areaAve(Variable,Location,Axis)

real areaAve("Variable", "Location", "Axis")

Returns the area-weighted average of the variable. For details, see areaAve (p. 31).

areaInt(Variable,Location,Axis)

real areaInt("Variable", "Location", "Axis")

Returns the result of the variable integrated over the 2D Location. For details, see areaInt (p. 31).

ave(Variable,Location)

real ave("Variable", "Location")

Returns the arithmetic average of the variable. For details, see ave (p. 32).

calcTurboVariables()

void calcTurboVariables()

Calculates all 'extra' turbo variables. (Works only in turbo mode.)

calculate()

void calculate(function,...)

Evaluates the named function with the supplied argument list, and returns the float result. The function name is arequired argument, which can be followed by a variable length list of arguments.

calculateUnits()

string calculateUnits(function,...)

Evaluates the named function with the supplied argument list, and returns the value and units.

collectTurboInfo()This is an internal subroutine that is used only to initialize report templates.

comfortFactors()This is an internal subroutine that is used only to initialize report templates.

compressorPerform()This is a special macro; for details, see Gas Compressor Performance Macro (p. 212). For example:

compressorPerform("Inlet", "Outlet", "Blade", "X", 600, 0.03, 10, 1.2)

compressorPerformTurbo()This is an internal subroutine that is used only to initialize report templates.

copyFile(FromPath,ToPath)A utility function for copying files.




void copyFile("FromPath", "ToPath")

count(Location)

real count("Location")

Returns the number of nodes on the location. For details, see count (p. 33).

countTrue(Expression, Location)The countTrue function returns the number of mesh nodes on the specified region that evaluate to “true”, wheretrue means greater than or equal to 0.5. The countTrue function is valid for 1D, 2D, and 3D locations. For details,see countTrue (p. 33).

real countTrue( "Expression", "Location" )

where "Expression" contains one of the logical operators =, >, <, <=, or >=.

cpPolar()This is a special macro; for details, see Cp Polar Plot Macro (p. 212). For example:

cpPolar("Plane 1", "Y", 0.3, "X", "Inlet", 10000)

evaluate(Expression)

real,string evaluate("Expression")

Returns the value of the expression and the units. Only one expression can be evaluated each time the subroutineis executed. The main advantage of using evaluate is that it takes any CEL expression. This means that you donot have to learn any other quantitative power syntax routines described in this section. Also, evaluate will returnthe result units in addition to the value.

An example is:

evaluate("areaAve(Velocity v)\@Location 1")

In this case, another subroutine is evaluated. The evaluate command takes an any expression as the argument,or more precisely, any expression that resolves to a quantity. This means that you cannot use:

"2*Pressure"

but you can use:

"2*minVal(Pressure)\@locator 1"

or

"100 [m]"

This is simply an alternative way of typing:

! $myVal = 2 * minVal("Pressure", "Location");

The reason that the @ is escaped calling evaluate() is to avoid Perl treating it as a special character.

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evaluateInPreferred(Expression)

real,string evaluateInPreferred("Expression")

Returns the value of the expression in your preferred units. Preferred units are the units of the data that CFD-Postuses when information is displayed to you and are the default units when you enter information (as contrasted withunits of the data that are stored in results files). Use the Edit > Options > Common > Units dialog to set yourpreferred units.

exprExists(Expression)

bool exprExists( "Expression" )

Returns true if an expression with this name exists; false otherwise.

fanNoiseDefault()This is an internal subroutine that is used only to initialize report templates.

fanNoise()This is an internal subroutine that is used only to initialize report templates.

force(Location,Axis)

real force("Location", "Axis")

Returns the force value. For details, see force (p. 34).

forceNorm(Location,Axis)

real forceNorm("Location", "Axis")

Returns the forceNorm value. For details, see forceNorm (p. 35).

getBladeForceExpr()This is an internal subroutine that is used only to initialize report templates.

getBladeTorqueExpr()This is an internal subroutine that is used only to initialize report templates.

getCCLState()This is an internal debugging call.

getChildrenByCategory()

SV* getChildrenByCategory()

Return the children of an object that belong to the specified category in a comma-separated list. Use 'split ","'to convert the string into an array of strings.

getChildren()

SV* getChildren(objName, childType)

Return the children of an object in a comma separated list. If childType is not an empty string, this subroutinereturn only children of the specified type.




getExprOnLocators()This is an internal subroutine that is used only to initialize report templates.

getExprString(Expression)

string getExprString( "Expression" )

Returns the value and the units of the expression in the form “value units”. For example: “100 m”

getExprVal(Expression)

real getExprVal( "Expression" )

Returns only the "value" portion of the expression (units are not included).

getParameterInfo()

SV* getParameterInfo(objName, paramName, infoType)

Returns the requested information for a parameter of an object.

getParameters()

SV* getParameters(objName)

Returns the parameters of an object in a comma-separated list. Use 'split ","' to convert the string into an arrayof strings.

getTempDirectory()

char getTempDirectory()

Returns the temporary directory path.

getType()

SV* getType(objName)

Returns the object type.

getValue(Object Name,Parameter Name)A utility function that takes a CCL object and parameter name and returns the value of the parameter.

getValue("Object Name", "Parameter Name")

Returns the value stored in Parameter Name.

Example1. Create a text object called Text 1.

2. In the Text String box, enter Here is a text string.

3. Click Apply to create the text object.

4. In the Command Editor dialog box, enter the following:

!string = getValue( "/TEXT:Text 1/TEXT ITEM: Text Item 1", "Text String");! print $string;

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5. Click Process, and the string will be printed to your terminal window.

The same procedure can be carried out for any object.

getViewArea()

void getViewArea()

Calculates the area of the scene projected in the view direction. Returns the area and the units.

isCategory()

int isCategory(objName, category)

A return of 1 indicates that the object matches the passed category; 0 otherwise.

Length(Location)

real Length("Location")

Returns the value of length. For details, see length (p. 36).

NoteWhile using this function in Power Syntax the leading character is capitalized to avoid confusion withthe Perl internal command “length.”

lengthAve(Variable,Location)

real lengthAve("Variable", "Location")

Returns the length-based average of the variable on the line locator. For details, see lengthAve (p. 36).

lengthInt(Variable,Location)

real lengthInt("Variable", "Location")

Returns the length-based integral of the variable on the line locator. For details, see lengthInt (p. 37).

liquidTurbPerformTurbo()This is an internal subroutine that is used only to initialize report templates.

liquidTurbPerform()This is an internal subroutine that is used only to initialize report templates.

massFlow(Location)

real massFlow("Location")

Returns the mass flow through the 2D locator. For details, see massFlow (p. 37).

massFlowAve(Variable,Location)

real massFlowAve("Variable", "Location")

Returns the calculated value of the variable. For details, see massFlowAve (p. 38).




massFlowAveAbs()This is an internal subroutine that is used only to initialize report templates.

massFlowInt(Variable,Location)

real massFlowInt("Variable","Location")

Returns the calculated value of the variable. For details, see massFlowInt (p. 40).

maxVal(Variable,Location)

real maxVal("Variable", "Location")

Returns the maximum value of the variable at the location. For details, see maxVal (p. 41).

minVal(Variable,Location)

real minVal("Variable", "Location")

Returns the minimum value of the variable at the location. For details, see minVal (p. 41).

objectExists()

int objectExists(objName)

A return of 1 indicates that the object exists; 0 otherwise.

probe(Variable,Location)

real probe("Variable", "Location")

ImportantThis calculation should only be performed for point locators described by single points. Incorrect solutionswill be produced for multiple point locators.

Returns the value of the variable at the point locator. For details, see probe (p. 42).

pumpPerform()This is an internal subroutine that is used only to initialize report templates.

pumpPerformTurbo()This is an internal subroutine that is used only to initialize report templates.

range(Variable,Location)

(real, real) range("Variable", "Location")

Returns the minimum and maximum values of the variable at the location.

reportError(String)

void reportError( "String" )

Pops up an error dialog.

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reportWarning(String)

void reportWarning( "String" )

Pops up a warning dialog.

showPkgs()

void showPkgs()

Returns a list of packages available which may contain other variables or subroutines in Power Syntax.

showSubs()

void showSubs("String packageName")

Returns a list of the subroutines available in the specified package. If no package is specified, CFD-Post is used bydefault.

showVars()

void showVars("String packageName")

Returns a list of the Power Syntax variables and their current value defined in the specified package. If no packageis specified, CFD-Post is used by default.

spawnAsyncProcess()

int spawnAsyncProcess(cmd, args)

Spawns a forked process.

sum(Variable,Location)

real sum("Variable", "Location")

Returns the sum of the variable values at each point on the locator. For details, see sum (p. 42).

torque(Location,Axis)

real torque("Location", "Axis")

Returns the computed value of torque at the 2D locator about the specified axis. For details, see torque (p. 43).

turbinePerform()This is an internal subroutine that is used only to initialize report templates.

turbinePerformTurbo()This is an internal subroutine that is used only to initialize report templates.

verboseOn()Returns 1 or 0 depending if the Perl variable $verbose is set to 1.




volume(Locator)

real volume("Location")

Returns the volume of a 3D locator. For details, see volume (p. 43).

volumeAve(Variable,Location)

real volumeAve("Variable", "Location")

For details, see volumeAve (p. 43).

volumeInt(Variable,Locator)

real volumeInt("Variable", "Location")

For details, see volumeInt (p. 44).

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Chapter 9. Line Interface ModeThis chapter contains information on how to perform typical user actions (loading, printing, and so on), creategraphical objects, and perform quantitative calculations when running CFD-Post in Line Interface mode.

All of the functionality of CFD-Post can be accessed when running in Line Interface mode. In Line Interface mode,you are simply entering the commands that would otherwise be issued by the GUI. A viewer is provided in a separatewindow that will show the geometry and the objects that are created on the command line.

To run in Line Interface mode:

• Windows: Execute the command <CFXROOT>\bin\cfdpost -line at the DOS command prompt (omittingthe -line option will start the GUI mode).

You may want to change the size of the MS-DOS window to view the output from commands such as getstate.This can be done by entering mode con lines=X at the command prompt before entering CFD-Post, whereX is the number of lines to display in the window. You may choose a large number of lines if you want to beable to see all the output from a session (a scroll bar will appear in the DOS window). Note that once insideCFD-Post, file paths should contain a forward slash / (and not the backslash that is required in MS-DOS).

• UNIX: Execute the command <CFXROOT>/bin/cfdpost -line at the command prompt (omitting the-line option will start the GUI mode).

In CFD-Post Line Interface mode, all commands are assumed to be actions, the > symbol required in the CommandEditor dialog box is not needed. To call up a list of valid commands, type help at the command prompt.

All of the functionality available from the Command Editor dialog box in the GUI is available in Line Interfacemode by typing enterccl or e at the command prompt. When in e mode, you can enter any set of valid CCLcommands. The commands are not processed until you leave e mode by typing .e. You can cancel e mode withoutprocessing the commands by typing .c. For details, see Command Editor (p. 226).

An explanation and list of command actions are available. For details, see Overview of Command Actions (p. 129).(The action commands shown in this link are preceded by a > symbol. This should be omitted when entering actioncommands at the command prompt.)

You can create objects by entering the CCL definition of the object when in e mode, or by reading the objectdefinition from a session or state file. For details, see File Operations from the Command Editor Dialog Box (p. 130).

In summary, Line Interface mode differs from the Command Editor dialog box because Line Interface actioncommands are not preceded by a > symbol. In the same way, when entering lines of CCL or Power Syntax, e mustbe typed (whereas this is not required in the Command Editor dialog box). It should be noted that these are theonly principal differences, and all commands that work for the Command Editor dialog box will also work in LineInterface mode, providing the correct syntax is used.

Features Available in Line Interface ModeThe following features are available in line interface mode:

Viewer HotkeysThe zoom, rotate, pan and other mouse actions available for manipulating the Viewer in the GUI performidentical functions in the Viewer in Line Interface mode. In addition to this, hotkeys can be used to manipulateother aspects of the Viewer. For a full list of all the hotkeys available, click in the Viewer to make it the activewindow and select the ? icon. To execute a hotkey command, click once in the Viewer (or on the object, assome functions are object-specific) and type the command.

CalculatorWhen functions are evaluated from the command line, the result is simply printed to standard output.

For a list of valid calculator functions and required parameters, type calculate help at the commandprompt. Additional information is available; for details, see Quantitative Calculations in the Command EditorDialog Box (p. 136).

Viewing All Currently Defined Objects (getstate Command)The list of all currently defined objects can be obtained using the getstate command. To get details on aspecific object, type getstate <ObjectName>.

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Viewing a ChartYou can view a chart object in the Chart Viewer using the chart <ChartObjectName> command.

Repeating CCL CommandsIf you want to repeat the most recent CCL command, type: =

Executing a UNIX Shell CommandIf you want to carry out a UNIX shell command, type % directly before your command. For example, %lswill list all the files in your current directory.

Quitting a Command Line Interface SessionTo end you CFD-Post command line interface session from the command prompt, enter: quit

Example. The following example provides a set of commands that you could enter at the CFX> command prompt.The output written to the screen when executing these commands is not shown.

CFX> load filename=c:/MyFiles/StaticMixer.resCFX> getstate StaticMixer DefaultCFX> eBOUNDARY:StaticMixer DefaultVisibility = OnTransparency = 0.5END.eCFX> quit



Features Available in Line Interface Mode

GlossarySymbols<CFXROOT> The directory in which CFX is installed; for example: C:\Program Files\ANSYS

Inc\v120\CFX\

Aabsolute pressure The summation of solver pressure, reference pressure, and hydro-static pressure (if a buoyant

flow) in the cavitation model. The absolute pressure is clipped to be no less than the vaporpressure of the fluid. It is used by the solver to calculate pressure-dependent properties (suchas density for compressible flow).

absorption coefficient A property of a medium that measures the amount of thermal radiation absorbed per unitlength within the medium.

adaption See mesh adaption.

adaption criteria The criteria that are used to determine where mesh adaption takes place.

adaption level The degree that a mesh element has been refined during adaption. Each mesh element hasan adaption level. Each time an element is split into smaller elements, the new elementshave an adaption level that is one greater than the "parent" element. The maximum numberof adaption levels is controlled to prevent over-refinement.

adaption step One loop of the adapt-solve cycle in the mesh adaption process.

Additional Variable A non-reacting, scalar component. Additional Variables are used to model the distributionof passive materials in the flow, such as smoke in air or dye in water.

Additional Variables are typically specified as concentrations.

adiabatic The description of any system in which heat is prevented from crossing the boundary ofthe system. You can set adiabatic boundary conditions for heat transfer simulations inANSYS CFX or in ANSYS FLUENT.

Advancing Front and Inflation(AFI)

The default meshing mode in CFX. The AFI mesher consists of a triangularsurface/tetrahedral volume mesh generator that uses the advancing front method to discretizefirst the surface and then the volume into an unstructured (irregular) mesh. Inflation can beapplied to selected surfaces to produce prismatic elements from the triangular surface mesh,which combine with the tetrahedra to form a hybrid mesh.

all domains In immersed-solids cases in CFD-Post, “all domains” refers to all of the domains in the caseexcluding the immersed solid. This is done for backwards compatibility.

Generally speaking, only the wireframe needs to keep track of both “all domains” and theimmersed solid.

ASM (Algebraic Slip Model) A mathematical form in which geometry may be represented, known as parametric cubic.

aspect ratio Also known as normalized shape ratio. A measure of how close to a regular tetrahedronany tetrahedron is. The aspect ratio is 1 for a regular tetrahedron, but gets smaller the flatterthe tetrahedron gets. Used for judging how good a mesh is.

Bbackup file An intermediate CFX-Solver Results file that can be manually generated during the course

of a solution from the CFX-Solver Manager interface by using the Backup action button.Backup files should be generated if you suspect your solution may be diverging and wantto retain the intermediate solution from which you can do a restart.

batch mode A way to run some components of ANSYS CFX without needing to open windows to controlthe process. When running in batch mode, a Viewer is not provided and you cannot enter

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commands at a command prompt. Commands are issued via a CFD-Post session file(*.cse), the name of which is specified when executing the command to start batch mode.The session file can be created using a text editor, or, more easily, by recording a sessionwhile running in line-interface or GUI mode.

blend factor A setting that controls the degree of first/second order blending for the advection terms indiscrete finite volume equations.

body A collection of surfaces that completely and unambiguously enclose a finite volume.Modelers that create so-called B-Rep models create "bodies." This term was coined todistinguish between the tri-parametric entities, known herein as solids, and the shell-likerepresentations produced by most CAD systems.

boundary A surface or edge that limits the extent of a space. A boundary can be internal (the surfaceof a submerged porous material) or external (the surface of an airfoil).

boundary condition Physical conditions at the edges of a region of interest that you must specify in order tocompletely describe a simulation.

Boussinesq model See buoyant flow.

buoyant flow Flow that is driven wholly or partially by differences in fluid density. For fluids wheredensity is not a function of temperature, pressure, or Additional Variables, the Boussinesqapproximation is employed. If density is a function of one of these, then the Full Buoyancymodel is employed.

CCEL (CFX ExpressionLanguage)

A high level language used within CFX to develop expressions for use in your simulations.CEL can be used to apply user-defined fluid property dependencies, boundary conditions,and initial values. Expressions can be developed within CFX using the Expression Editor.

CFD (Computational FluidDynamics)

The science of predicting fluid flow, heat transfer, mass transfer (as in perspiration ordissolution), phase change (as in freezing or boiling), chemical reaction (as in combustion),mechanical movement (as in fan rotation), stress or deformation of related solid structures(such as a mast bending in the wind), and related phenomena by solving the mathematicalequations that govern these processes using a numerical algorithm on a computer.

CFX-Solver Input file A file that contains the specification for the whole simulation, including the geometry,surface mesh, boundary conditions, fluid properties, solver parameters and any initial values.It is created by CFX and used as input to CFX-Solver.

CHT (Conjugate Heat Transfer) Heat transfer in a conducting solid.

clipping plane A plane that is defined through the geometry of a model, in front of which no geometry isdrawn. This enables you to see parts of the geometry that would normally be hidden.

command actions Command actions are:

• Statements in session files

• Commands entered into the Tools > Command Editor dialog box

• Commands entered in Line Interface mode.

All such actions must be preceded with the > symbol. These commands force CFD-Post toundertake specific tasks, usually related to the input and output of data from the system.See also Power Syntax (p. 161).

component A substance containing one or more materials in a fixed composition. The properties of acomponent are calculated from the mass fractions of the constituent materials and are basedon the materials forming an ideal mixture.

compressible flow Flow in which the fluid volume changes in response to pressure change. Compressible floweffects can be taken into consideration when the Mach number (M) approaches approximately0.2.

computational mesh A collection of points representing the flow field where the equations of fluid motion (andtemperature, if relevant) are calculated.



control volume The volume surrounding each node, defined by segments of the faces of the elementsassociated with each node. The equations of fluid flow are solved over each control volume.

conservative values See corrected boundary node values.

convergence A state of a solution that occurs when the change in residual values from one iteration tothe next are below defined limits.

corrected boundary node values Node values obtained by taking the results produced by CFX-Solver (called "conservativevalues") and overwriting the results on the boundary nodes with the specified boundaryconditions.

The values of some variables on the boundary nodes (that is, on the edges of the geometry)are not precisely equal to the specified boundary conditions when CFX-Solver finishes itscalculations. For instance, the value of velocity on a node on the wall will not be preciselyzero, and the value of temperature on an inlet may not be precisely the specified inlettemperature. For visualization purposes, it can be more helpful if the nodes at the boundarydo contain the specified boundary conditions and so "corrected boundary node values" areused. Corrected boundary node values are obtained by taking the results produced byCFX-Solver (called "conservative values") and overwriting the results on the boundarynodes with the specified boundary conditions. This will ensure the velocity is display aszero on no-slip walls and equal to the specified inlet velocity on the inlet, for example.

coupled solver A solver in which all of the hydrodynamic equations are solved simultaneously as a singlesystem. The advantages of a coupled solver are that it is faster than a traditional solver andfewer iterations are required to obtain a converged solution. CFX-Solver is an example ofa coupled solver.

curve A general vector valued function of a single parametric variable. In CFX, a line is also acurve. By default, curves are displayed in yellow in ANSYS CFX.

Ddefault boundary condition The boundary condition that is applied to all surfaces that have no boundary condition

explicitly set. Normally, this is set to the No Slip Adiabatic Wall boundary condition,although you can change the type of default boundary condition in CFX.See Also boundary condition.

Detached Eddy Simulation(DES)

A model that covers the boundary layer by a RANS model and switches to a LES model indetached regions.

Direct Numerical Simulation(DNS)

A CFD simulation in which the Navier-Stokes equations are solved without any turbulencemodel.

discretization The equations of fluid flow cannot be solved directly. Discretization is the process by whichthe differential equations are converted into a system of algebraic equations, which relatethe value of a variable in a control volume to the value in neighboring control volumes.See Also Navier-Stokes equations.

domain Regions of fluid flow and/or heat transfer in CFX are called domains. Fluid domains definea region of fluid flow, while solid domains are regions occupied by conducting solids inwhich volumetric sources of energy can be specified. The domain requires threespecifications:

• The region defining the flow or conducting solid. A domain is formed from one or more3D primitives that constrain the region occupied by the fluid and/or conducting solids.

• The physical nature of the flow. This determines the modeling of specific features suchas heat transfer or buoyancy.

• The properties of the materials in the region.

There can be many domains per model, with each domain defined by separate 3D primitives.Multidomain problems may be created from a single mesh if it contains multiple 3Dprimitives or is from multiple meshes.

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dynamic viscosity Dynamic viscosity, also called absolute viscosity, is a measure of the resistance of a fluidto shearing forces.

dynamical time For advection dominated flows, this is an approximate timescale for the flow to movethrough the Domain. Setting the physical time step (p. 160) size to this value (or a fractionof it) can promote faster convergence.

Eeddy viscosity model A turbulence model based on the assumption that Reynolds stresses are proportional to

mean velocity gradients and that the Reynolds stress contribution can be described by theaddition of a turbulent component of viscosity. An example of an eddy viscosity model isthe k-ε model.

edge The edge entity describes the topological relationships for a curve. Adjacent faces share atleast one edge.

emissivity A property of an object that describes how much radiation it emits as compared to that ofa black body at the same temperature.

expansion factor The rate of growth of volume elements away from curved surfaces and the rate of growthof surface elements away from curved boundaries. Expansion factor is also used to specifythe rate of mesh coarsening from a mesh control.

expression editor An interactive, form-driven facility within CFX for developing expressions.See Also CEL (CFX Expression Language).

Expression Language See CEL (CFX Expression Language).

external flow A flow field that is located outside of your geometry.See Also internal flow.

Fface “Face” can have several meanings:

• A solid face is a surface that exists as part of a solid. It is also known as an implicitsurface.

• An element face is one side of a mesh element.

• A boundary face is an element face that exists on the exterior boundary of the domain.

• Surfaces composed of edges that are connected to each other.

FLEXlm The program that administers ANSYS licensing.

fluid domain See domain.

flow boundaries The surfaces bounding the flow field.

flow region A volumetric space containing a fluid. Depending on the flow characteristics, you may havea single, uninterrupted flow region, or several flow regions, each exhibiting differentcharacteristics.

flow symmetry Flow where the conditions of the flow entering and leaving one half of a geometry are thesame as the conditions of the flow entering and leaving the other half of the geometry.

fluid A substance that tends to flow and assumes the shape of its domain, such as a gas in a ductor a liquid in a container.

free edges Element edges belonging to only one element.

Ggas or liquid surface A type of boundary that exhibits no friction and fluid cannot move through it. Also called

a symmetry boundary.



general fluid A fluid whose properties may be generally prescribed in ANSYS CFX or ANSYS FLUENT.Density and specific heat capacity for general fluids may depend on pressure, temperature,and any Additional Variables.See Also ideal gas.

global model tolerance The minimum distance between two geometry entities below which CFX considers themto be coincident. The default setting of global model tolerance, defined in the templatedatabase, is normally .005 in whichever geometry units you are working.

geometric symmetry The state of a geometry where each half is a mirror of the other.

group A named collection of geometric and mesh entities that can be posted for display inviewports. The group's definition includes:

• Group name

• Group status (current/not current)

• Group display attributes (modified under Display menu)

• A list of the geometric and mesh entities that are members of the group.

Hhexahedral element A mesh element with the same topology as a hexahedron, with six faces and eight vertices.

home directory The directory on all UNIX systems and some Windows NT systems where each user storesall of their files, and where various setup files are stored.

However, on some Windows NT systems, users do not have an equivalent to the UNIXhome directory. In this case, the ANSYS CFX setup file cfx5rc can be placed inc:\winnt\profiles\<user>\Application Data\ANSYS CFX\<release>,where <user> is the user name on the machine. Other files can be put into a directory setby the variable HOME.

hybrid values See corrected boundary node values.

Iideal gas A fluid whose properties obey the ideal gas law. The density is automatically computed

using this relationship and a specified molecular weight.

IGES (Initial GraphicsExchange Specification) file

An ANSI standard formatted file used to exchange data among most commercial CADsystems. IGES files can be imported into CFX.

implicit geometry Geometry that exists as part of some other entity. For example, the edges of a surface areimplicit curves.

import mesh A meshing mode that allows import of volume meshes generated in one of a number ofexternal CFD packages. The volume mesh can contain hexahedral, tetrahedral, prismatic,and pyramidal element types.

inactive region A fluid or porous region where flow and (if relevant) temperatures are not being calculated,or a solid region where temperatures are not being calculated. By default, inactive regionsare hidden from view in the graphics window.

incompressible flow Flow in which the density is constant throughout the domain.

incremental adaption The method of mesh adaption used by CFX where an existing mesh is modified to meetspecified criteria. Incremental adaption is much faster than re-meshing; however, the meshquality is limited by that of the initial mesh.

inertial resistance coefficients Mathematical terms used to define porous media resistance.

initial guess The values of dependent variables at the start of a steady state simulation. These can setexplicitly, read from an existing solution, or given default values.

initial values The values of dependent variables at the initial time of a transient simulation. These can beeither set explicitly, or read from an existing solution.

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inlet boundary condition A boundary condition (p. 154) for which the quantity of fluid flowing into the flow domainis specified, for example, by setting the fluid velocity or mass flow rate.

instancing The process of copying an object and applying a positional transform to each of the copies.For example, a row of turbine blades can be visualized by applying instancing to a singleblade.

interior boundary A boundary that allows flow to enter and exit. These types of boundaries are useful toseparate two distinct fluid regions from each other, or to separate a porous region from afluid region, when you still want flow to occur between the two regions.

internal flow Flow through the interior of your geometry, such as flow through a pipe.See Also external flow.

interpolation The process of transferring a solution from a results file containing one mesh onto a secondfile containing a different mesh.

isentropic The description of a process where there is no heat transfer and entropy is held constant.

isosurface A surface of constant value for a given variable.

A three-dimensional surface that defines a single magnitude of a flow variable such astemperature, pressure, velocity, etc.

Isovolume A locator that consists of a collection of volume elements, all of which take a value of avariable greater than a user-specified value.

JJPEG file A common graphics file type that is supported by CFD-Post output options.

Kk-epsilon turbulence model A turbulence model (p. 164) based on the concept that turbulence consists of small eddies

that are continuously forming and dissipating. The k-epsilon turbulence model solves twoadditional transport equations: one for turbulence generation (k), and one for turbulencedissipation (epsilon).

key See legend.

kinematic diffusivity A function of the fluid medium that describes how rapidly an Additional Variable wouldmove through the fluid in the absence of convection.

Llaminar flow Flow that is dominated by viscous forces in the fluid, and characterized by low Reynolds

Number.

A flow field is laminar when the velocity distributions at various points downstream of thefluid entrance are consistent with each other and the fluid particles move in a parallel fashionto each other. The velocity distributions are effectively layers of fluid moving at differentvelocities relative to each other.

Large Eddy Simulation Model(LES)

The Large Eddy Simulation model decomposes flow variables into large and small scaleparts. This model, solves for large-scale fluctuating motions and uses “sub-grid” scaleturbulence models for the small-scale motion.

legend A color key for any colored plot.

line interface mode A mode in which you type the commands that would otherwise be issued by the GUI. Aviewer is provided that shows the geometry and the objects created on the command line.Line interface mode differs from entering commands in the Command Editor dialog boxin that line interface action commands are not preceded by a > symbol. Aside from thatdifference, all commands that work for the Command Editor dialog box will also work inline interface mode, providing the correct syntax is used.



locator A place or object upon which a plot can be drawn. Examples are planes and points.

MMAlt key (Meta key) The MAlt key (or Meta key) is used to keyboard select menu items with the use of

mnemonics (the underscored letter in each menu label). By simultaneously pressing theMAlt key and a mnemonic is an alternative to using the mouse to click on a menu title. TheMAlt key is different for different brands of keyboards. Some examples of MAlt keysinclude the " " key for Sun Model Type 4 keyboards, the "Compose Character" key forTektronix keyboards, and the “Alt” key on most keyboards for most Windows-based systems.

mass fraction The ration of the mass of a fluid component to the total mass of the fluid. Values for massfraction range from 0 to 1.

material A substance with specified properties, such as density and viscosity.

meridional A term used in ANSYS FLUENT documentation that is equivalent to the ANSYS CFXterm ”constant streamwise location”.

mesh A collection of points representing the flow field where the equations of fluid motion (andtemperature, if relevant) are calculated.

mesh adaption The process by which, once or more during a run, the mesh is selectively refined at variouslocations, depending on criteria that you can specify. As the solution is calculated, the meshcan automatically be refined in locations where solution variables are changed rapidly, inorder to resolve the features of the flow in these regions.

There are two general methods for performing mesh adaption. Incremental adaption takesan existing mesh and modifies it to meet the adaption criteria. The alternative is re-meshing,in which the whole geometry is re-meshed at every adaption step according to the adaptioncriteria. In CFX, incremental adaption is used because this is much faster; however, thisimposes the limitation that the resulting mesh quality is limited by the quality of the initialmesh.

mesh control A refinement of the surface and volume mesh in specific regions of the model. Mesh controlscan take the form of a point, line, or triangle.

meshing mode The method you use to create your mesh of nodes and elements required for analysis. Thereare two main meshing modes:

• Advancing Front and Inflation (AFI) (p. 153)

• import mesh (p. 157)

minimal results file A file that contains only the results for selected variables, and no mesh. It can be createdonly for transient calculations. It is useful when you are only interested in particular variablesand want to minimize the size of the results for the transient calculation.

multicomponent fluid A fluid consisting of more than one component. The components are assumed to be mixedat the molecular level, though the proportions of each component may vary in space or time.The properties of a multicomponent fluid are dependent on the proportion of constituentcomponents.

NNavier-Stokes equations The fundamental equations of fluid flow and heat transfer, solved by CFX-Solver. They

are partial differential equations.

new model preferences Preferential settings for your model that define the meshing mode (p. 159), the geometryunits, and the global model tolerance (p. 157).

node allocation parameter A parameter that is used in mesh adaption (p. 159) to determine how many nodes are addedto the mesh in each adaption step (p. 153).

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non-clipped absolute pressure The summation of solver pressure, reference pressure, and hydro-static pressure (if a buoyantflow). This pressure, used by the solver to calculate cavitation sources, can be negative orpositive.

non-Newtonian fluid A fluid that does not follow a simple linear relationship between shear stress and shearstrain.

normal The direction perpendicular to the surface of a mesh element or geometry. The positivedirection is determined by the cross-product of the local parametric directions in the surface.

normalized shape ratio See aspect ratio.

Oopen area The area in a porous region that is open to flow.

OpenGL A graphics display system that is used on a number of different types of computer operatingsystems.

outlet A boundary condition where the fluid is constrained to flow only out of the domain.

outline plot A plot showing the outline of the geometry. By setting the edge angle to 0, the surface meshcan be displayed over the whole geometry.

output file A text file produced by CFX-Solver that details the history of a run. It is important to browsethe output file when a run is finished to determine whether the run has converged, andwhether a restart is necessary.

Pparallel runs Separate solutions of sections (partitions) of your CFD model, run on more than one

processor.

parametric equation Any set of equations that express the coordinates of the points of a curve as functions ofone parameter, or express the coordinates of the points of a surface as functions of twoparameters, or express the coordinates of the points of a solid as functions of three parameters.

parametric solids Six-sided solids parameterized in three normalized directions. Parametric solids are coloredblue ANSYS CFX.

parametric surfaces Four sided surfaces parameterized in two normalized directions. Parametric surfaces arecolored green ANSYS CFX.

Particle-Particle Collision Model(LPTM-PPCM)

A model in ANSYS CFX that takes inter-particle collisions and their effects on the particleand gas phase into consideration.

periodic pair boundary condition A boundary condition where the values on the first surface specified are mapped to thesecond surface. The mapping can be done either by a translation or a rotation (if a rotatingframe of reference is used).

physical time step The time represented in each iteration of the solution.

pick list The list processor interprets the contents of all selected data boxes. All selected data boxesin CFX expect character strings as input. The character strings may be supplied by thegraphics system when you select an entity from a viewport, or you can type or paste in thestring directly. The character strings are called "pick lists."

plot Any means of viewing the results in CFD-Post. Types of plots include vectors, streamlines,and contour plots.

point An ordered n-tuple, where n is the number of dimensions of the space in which the pointresides.

point probes Points placed at specific locations in a computational domain where data can be analyzed.

polyline A locator that consists of user-defined points.

post-processor The component used to analyze and present the results of the simulation. For ANSYS CFX,the post-processor is CFD-Post.



Power Syntax The CFX Command Language (CCL) is the internal communication and command languageof CFD-Post. It is a simple language that can be used to create objects or perform actionsin the post-processor. Power Syntax enables you to embed Perl commands into CCL toachieve powerful quantitative post-processing.

Power Syntax programming uses the Perl programming language to allow loops, logic, andcustom macros (subroutines). Lines of Power Syntax are identified in a .ccl file by anexclamation mark (!) at the start of each line. In between Perl lines, simple syntax lines mayrefer to Perl variables and lists.

For details, see Power Syntax in ANSYS CFX (p. 137).

pre-processor The component used to create the input for the solver. For ANSYS CFX, the pre-processoris CFX-Pre.

pressure In the cavitation model, pressure is the same as solver pressure, but clipped such that theabsolute pressure is non-negative. It is used for post-processing only.

prism or prismatic element A 3D mesh element shaped like a triangular prism (with six vertices). Sometimes knownas a wedge element.

PVM (Parallel Virtual Machine) The environment that controls parallel processes.

PVMHosts file The database file containing information about where ANSYS CFX, and consequentlyPVM, have been installed on each PVM node. It is consulted when the Parallel VirtualMachine is started to determine where PVM is located on each slave node.

pyramid element A 3D mesh element that has five vertices.

Rreference coordinate frame The coordinate frame in which the principal directions of X or Y or Z are taken. X is taken

in the local X of that frame, etc. If the coordinate frame is a non-rectangular coordinateframe, then the principal axes 1, 2, and 3 will be used to define the X, Y, and Z directions,respectively. The default is CFX global system (Coord 0).

For domains, boundary conditions, and initial values, the reference coordinate frame isalways treated as Cartesian, irrespective of coordinate frame type.

region An area comprised of a fluid, a solid material, or a porous material.

residuals The change in the value of certain variables from one iteration to the next.

The discretized Navier-Stokes equations (p. 159) are solved iteratively. The residual for eachequation gives a measure of how far the latest solution is from the solution in the previousiteration. A solution is considered to be converged when the residuals are below a certainvalue.

CFX-Solver writes the residuals to the output file (p. 160) so that they can be reviewed.ANSYS FLUENT allows residuals to be plotted during the solution process.

results file (CFX-Solver Resultsfile)

A file produced by CFX-Solver that contains the full definition of the simulation as well asthe values of all variables throughout the flow domain and the history of the run includingresiduals (p. 161). An CFX-Solver Results file can be used as input to CFD-Post or as aninput file to CFX-Solver, in order to perform a restart.

Reynolds averagedNavier-Stokes (RANS)equations

Time-averaged equations of fluid motion that are primarily used with turbulent flows.

Reynolds stress The stress added to fluid flow due to the random fluctuations in fluid momentum in turbulentflows. When the Navier-Stokes equations (p. 159) are derived for time averaged turbulentflow to take into account the effect of these fluctuations in velocity, the resulting equationshave six stress terms that do not appear in the laminar flow equations. These are known asReynolds stresses.

Reynolds stress turbulencemodel

A model that solves transport equations for the individual Reynolds stress components. Itis particularly appropriate where strong flow curvature, swirl, and separation are present.

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Reynolds stress models in general tend to be less numerically robust than eddy viscositymodels such as the k-epsilon turbulence model (p. 158).

RNG k-epsilon turbulencemodel

An alternative to the standard k-epsilon turbulence model (p. 158). It is based onrenormalization group analysis of the Navier-Stokes equations. The transport equations forturbulence generation and dissipation are the same as those for the standard k-epsilon model,but the model constants differ, and the constant Cε1 is replaced by the function Cε1RNG.

Rotating Frame of Reference(RFR)

A coordinate system that rotates. ANSYS CFX and ANSYS FLUENT can solve for fluidflow in a geometry that is rotating around an axis at a fixed angular velocity.

run A process that requires the specification of the CFX-Solver input file (and an initial valuesfile, if necessary), and produces an output file and a results file (if successful).

SSampling Plane A locator that is planar and consists of equally-spaced points.

scalar variable A variable that has only magnitude and not direction. Examples are temperature, pressure,speed (the magnitude of the velocity vector), and any component of a vector quantity.

Scale Adaptive Simulation(SAS) model

A shear stress transport model used primarily for unsteady CFD simulations, wheresteady-state simulations are not of sufficient accuracy and do not properly describe the truenature of the physical phenomena. Cases that may benefit from using the SAS-SST modelinclude:

• Unsteady flow behind a car or in the strong mixing behind blades and baffles insidestirred chemical reactors

• Unsteady cavitation inside a vortex core (fuel injection system) or a fluid-structureinteraction (unsteady forces on bridges, wings, etc.).

For these problems and others, the SAS-SST model provides a more accurate solution thanURANS models, where steady-state simulations are not of sufficient accuracy and do notproperly describe the true nature of the physical phenomena.

Second Moment Closure models Models that use seven transport equations for the independent Reynolds stresses and onelength (or related) scale; other models use two equations for the two main turbulent scales.

session file (CFX) A file that contains the records of all the actions in each interactive CFX session. It has theextension .ses.

Shear Stress Transport (SST) A −k ω based SST model that accounts for the transport of the turbulent shear stress andgives highly accurate predictions of the onset and the amount of flow separation underadverse pressure gradients.

singleton (CCL object) A singleton object that consists of an object type at the start of a line, followed by a : (colon).Subsequent lines may define parameters and child objects associated with this object. Theobject definition is terminated by the string END on a line by itself. The singleton objectfor a session file is declared like this:

SESSION: Session Filename = <filename>.cse END

The difference between a singleton object and a named object is that after the data has beenprocessed, a singleton can appear just once as the child of a parent object. However, theremay be several instances of a named object of the same type defined with different names.

slice plane A locator that is planar, and which consists of all the points that intersect the plane and themesh edges.

solid A material that does not flow when a force or stress is applied to it.

The general class of vector valued functions of three parametric variables.



solid sub-domain A region of the fluid domain that is occupied by a conducting solid. ANSYS CFX can modelheat transfer in such a solid; this is known as CHT (Conjugate Heat Transfer) (p. 154).

solver The component that solves the CFD problem, producing the required results.

solver pressure The pressure calculated by solving conservative equations; it can be negative or positive.In the .out file it is called Pressure.

spanwise coordinate A term used in ANSYS FLUENT documentation that is equivalent to the ANSYS CFXterm ”constant span”.

specific heat The ratio of the amount of heat energy supplied to a substance to its corresponding changein temperature.

specific heat capacity The amount of heat energy required to raise the temperature of a fixed mass of a fluid by1K at constant pressure.

speed of sound The velocity at which small amplitude pressure waves propagate through a fluid.

sphere volume A locator that consists of a collection of volume elements that are contained in or intersecta user-defined sphere.

state files Files produced by CFD-Post that contain CCL commands. They differ from session filesin that only a snapshot of the current state is saved to a file. You can also write your ownstate files using any text editor.

STP (Standard Temperature andPressure)

Defined as 0°C (273.15K) and 1 atm (1.013x105 Pa).

steady-state simulation A simulation that is carried out to determine the flow after it has settled to a steady state.Note that, even with time constant boundary conditions, some flows do not have asteady-state solution.

stream plot A plot that shows the streamlines of a flow. Stream plots can be shown as lines, tubes, orribbons.

streamline The path that a small, neutrally-buoyant particle would take through the flow domain,assuming the displayed solution to be steady state.

subdomains Regions comprising a solid or set of solids, within the region of bounding solids for a fluiddomain, that allow the prescription of momentum and energy sources. They can be used tomodel regions of flow resistance and heat source.

subsonic flow The movement of a fluid at a speed less than the speed of sound.

surface plot A plot that colors a surface according to the values of a variable. Additionally, you canchoose to display contours.

symmetry-plane boundarycondition

A boundary condition where all variables except velocity are mathematically symmetricand there can be no diffusion or flow across the boundary. Velocity parallel to the boundaryis also symmetric and velocity normal to the boundary is zero.

Ttemplate fluid One of a list of standard fluids with predefined properties that you can use 'as is', or use as

a template to create a fluid with your own properties.

thermal conductivity The property of a fluid that characterizes its ability to transfer heat by conduction.

A property of a substance that indicates its ability to transfer thermal energy between adjacentportions of the substance.

thermal expansivity The property of a fluid that describes how a fluid expands as the result of an increase intemperature. Also known as the coefficient of thermal expansion, β.

theta The angular coordinate measured about the axis of rotation following the right-hand rule.When looking along the positive direction of the axis of rotation, theta is increasing in theclockwise direction. Note that the theta coordinate in CFD-Post does not increase over 360°,even for spiral geometries that wrap to more than 360°.

timestep See physical time step.

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tolerance See global model tolerance.

topology The shape, node, edge, and face numbering of an element.

tracers Particles that follow a flow pathline. Used in viewing CFD results in order to visualize themechanics of the fluid flow.

transitions Portions of a mesh that are the result of meshing geometry with two opposing edges thathave different mesh seeds. This produces an irregular mesh.

turbulence intensity The ratio of the root-mean-square of the velocity fluctuations to the mean flow velocity.

A turbulence intensity of 1% or less is generally considered low and turbulence intensitiesgreater than 10% are considered high. Ideally, you will have a good estimate of the turbulenceintensity at the inlet boundary from external, measured data. For example, if you aresimulating a wind-tunnel experiment, the turbulence intensity in the free stream is usuallyavailable from the tunnel characteristics. In modern low-turbulence wind tunnels, thefree-stream turbulence intensity may be as low as 0.05%.

For internal flows, the turbulence intensity at the inlets is totally dependent on the upstreamhistory of the flow. If the flow upstream is under-developed and undisturbed, you can usea low turbulence intensity. If the flow is fully developed, the turbulence intensity may beas high as a few percent.

turbulence length scale A physical quantity related to the size of the large eddies that contain the energy in turbulentflows.

In fully-developed duct flows, the turbulence length scale is restricted by the size of theduct, since the turbulent eddies cannot be larger than the duct. An approximate relationshipcan be made between the turbulence length scale and the physical size of the duct that, whilenot ideal, can be applied to most situations.

If the turbulence derives its characteristic length from an obstacle in the flow, such as aperforated plate, it is more appropriate to base the turbulence length scale on the characteristiclength of the obstacle rather than on the duct size.

turbulence model A model that predicts turbulent flow (p. 164). The available turbulence models in ANSYSCFX are:

• k-epsilon turbulence model (p. 158)

• RNG k-epsilon turbulence model (p. 162)

• Reynolds stress turbulence model (p. 161)

• zero equation turbulence model (p. 166)

Turbulence models allow a steady state representation of (inherently unsteady) turbulentflow to be obtained.

turbulent A flow field that is irregular and chaotic look. In turbulent flow, a fluid particle's velocitychanges dramatically at any given point in the flow field, in time, direction, and magnitude,making computational analysis of the flow more challenging.

turbulent flow Flow that is randomly unsteady over time. A characteristic of turbulent flow is chaoticfluctuations in the local velocity.

Vvariable A quantity such as temperature or velocity for which results have been calculated in a CFD

calculation.

See also Additional Variable (p. 153).

vector plot A plot that shows the direction of the flow at points in space, using arrows. Optionally, thesize of the arrows may show the magnitude of the velocity of the flow at that point. Thevectors may also be colored according to the value of any variable.

verification A check of the model for validity and correctness.



viewer area The area of ANSYS CFX that contains the 3D Viewer, Table Viewer, Chart Viewer,Comment Viewer, and Report Viewer, which you access from tabs at the bottom of thearea.

viewport (CFX) An assigned, named, graphics window definition, stored in the CFX database, that can beused to display selected portions of a model's geometry, finite elements, and analysis results.The viewport's definition includes:

• The viewport name

• The status of the viewport (posted or unposted; current or not current)

• Viewport display attributes

• A definition of the current view

• A current group

• A list of the posted groups for display

• A graphics environment accessed from Display, Preference, and Group menus that iscommon to all viewports.

There are the following types of CFX viewports:

current viewportThe viewport currently being displayed. The following actions can be performed onlyon the current viewport:

• Changing the view by using the View menu or mouse.

• Posting titles and annotations by using the Display menu.

posted viewportA viewport that has been selected for display.

target viewportA viewport selected for a viewport modify action. Any viewport (including the currentviewport) can be selected as the target viewport.

viscosity The ratio of the tangential frictional force per unit area to the velocity gradient perpendicularto the flow direction.

viscous resistance coefficients A term to define porous media resistance.

Volume of Fluid (VOF) method A technique for tracking a fluid-fluid interface as it changes its topology.

Wwall A generic term describing a stationary boundary through which flow cannot pass.

wedge element See prism or prismatic element.

workspace area The area of CFX-Pre and CFD-Post that contains the Outline, Variables, Expressions,Calculators, and Turbo workspaces, which you access from the tabs at the top of the area.Each workspace has a tree view at the top and an editor at the bottom (which is often calledthe Details view).

See also CFD-Post Graphical Interface (p. 45).

Yy+ (YPLUS) A non-dimensional parameter used to determine a specific distance from a wall through the

boundary layer to the center of the element at a wall boundary.

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Zzero equation turbulence model A simple model that accounts for turbulence by using an algebraic equation to calculate

turbulence viscosity. This model is useful for obtaining quick, robust solutions for use asinitial fields for simulations using more sophisticated turbulence models.



IndexSymbols

AANSYS FLUENT field variables, 79area function, 30area(Location,Axis) power syntax subroutine, 141areaAve function, 31areaAve(Variable,Location,Axis) power syntax subroutine,142areaInt function, 31areaInt(Variable,Location,Axis) power syntax subroutine, 142ave function, 32ave(Variable,Location) power syntax subroutine, 142

Bbuoyant flow variables, 51

CcalcTurboVariables() power syntax subroutine, 142calculate() power syntax subroutine, 142calculateUnits() power syntax subroutine, 142Cartesian coordinate

variables, 48CCL (CFX command language)

names definition, 10overview, 9syntax, 9

CEL (CFX expression language), 13available system variables, 63conditional statement, 16constants, 14, 17examples, 18expression names, 63expression properties, 63expression syntax, 14expressions, 13, 17functions and constants, 15fundamentals, 13if statement, 16introduction, 13logical expressions, 14logical operators, 15mathematical expressions, 14mathematical operators, 15multiple-line expressions, 15offset temperature, 17operators and built-in functions, 15relational operators, 15scalar expressions, 63statements, 14technical details, 20unavailable system variables, 63units, 14

values - dimensionless, 13variables, 55

CEL limitationscreate Design Exploration expressions in CFD-Post, 13

CFX command language (CCL)names definition, 10overview, 9syntax, 9

CFX Launcher, 1adding APPLICATION objects, 5adding DIVIDER objects, 7adding GROUP objects, 4customizing, 4interface, 1using variables in APPLICATION objects, 7

CFX menu overview, 2CFXROOT

installation root directory, 153chart

viewing using the command line, 136collectTurboInfo() power syntax subroutine, 142comfortFactors() power syntax subroutine, 142command editor

action commands, 129exporting data, 134file operations, 130importing data from, 134loading a results file, 130printing from, 134reading session files, 130reading state files, 132readstate option actions, 133saving state file, 131

command line, 3mode, 151Windows, 3

comment character in CCL syntax, 10compressible flow variables, 51compressorPerform() power syntax subroutine, 142compressorPerformTurbo() power syntax subroutine, 142conditional statement, 16conservative variable values, 45constants in CEL, 14, 17continuation character, in CCL syntax, 11copyFile() power syntax subroutine, 142corrected boundary node values, 45count function, 33count(Location) power syntax subroutine, 143countTrue function, 33countTrue() power syntax subroutine, 143cpPolar() power syntax subroutine, 143

EEdit menu overview, 1enthalpy variables, 55evaluate(Expression) power syntax subroutine, 143evaluateInPreferred(Expression) power syntax subroutine, 144

167



examplescalculate area, 30CEL, 18feedback to control inlet temperature, 19load command, 130readsession command, 131readstate command, 133Reynolds number dependent viscosity, 18savestate command, 131

exportingdata using the command editor, 134

expressionproperties in CEL, 63

expression language, 13constants, 17expressions, 13statements, 14statements - multiple-line expressions, 15statements - syntax, 14units, 14using, 17values - dimensionless, 13

expression namesCEL, 63

expression syntax, 14expressions

create in CFD-Post for Design Exploration, 13in CEL, 17

exprExists() power syntax subroutine, 144

FfanNoise() power syntax subroutine, 144fanNoiseDefault() power syntax subroutine, 144File menu overview, 1file operations

from the command editor, 130force function, 34force(Location,Axis) power syntax subroutine, 144forceNorm function, 35forceNorm(Location,Axis) power syntax subroutine, 144functions

area, 30areaAve, 31areaInt, 31ave, 32count, 33countTrue, 33force, 34forceNorm, 35inside, 35length, 36lengthAve, 36lengthInt, 37mass, 37massAve, 37massFlow, 37massFlowAve, 38

massFlowInt, 40massInt, 41maxVal, 41minVal, 41probe, 42rmsAve, 42sum, 42torque, 43volume, 43volumeAve, 43volumeInt, 44

functions and constantsCEL, 15

GgetBladeForceExpr() power syntax subroutine, 144getBladeTorqueExpr() power syntax subroutine, 144getCCLState() power syntax subroutine, 144getChildren() power syntax subroutine, 144getChildrenByCategory() power syntax subroutine, 144getExprOnLocators() power syntax subroutine, 145getExprString() power syntax subroutine, 145getExprVal() power syntax subroutine, 145getParameterInfo() power syntax subroutine, 145getParameters() power syntax subroutine, 145getTempDirectory() power syntax subroutine, 145getType() power syntax subroutine, 145getValue(Object Name,Parameter Name) power syntaxsubroutine, 145getViewArea() power syntax subroutine, 146

HHelp menu overview, 3hybrid variable values, 45

Iif statement, 16importing

data from the command editor, 134indentation

in CCL syntax, 10inside function, 35isCategory() power syntax subroutine, 146

Llauncher, 1

adding APPLICATION objects, 5adding DIVIDER objects, 7adding GROUP objects, 4ANSYS menu overview, 2customizing, 4interface, 1Show menu, 2using variables in APPLICATION objects, 7

length function, 36Length(Location) power syntax subroutine, 146lengthAve function, 36



lengthAve(Variable,Location) power syntax subroutine, 146lengthInt function, 37lengthInt(Variable,Location) power syntax subroutine, 146line interface mode, 151liquidTurbPerform() power syntax subroutine, 146liquidTurbPerformTurbo() power syntax subroutine, 146lists

in CCL syntax, 11load command examples, 130loading

results file from the command editor, 130logical expressions, 14logical operators, 15

Mmass function, 37massAve function, 37massFlow function, 37massFlow(Location) power syntax subroutine, 146massFlowAve function, 38massFlowAve(Variable,Location) power syntax subroutine,146massFlowAveAbs function, 39massFlowAveAbs() power syntax subroutine, 147massFlowInt function, 40massFlowInt(Variable,Location) power syntax subroutine, 147massInt function, 41mathematical expressions, 14mathematical operators, 15maxVal function, 41maxVal(Variable,Location) power syntax subroutine, 147minVal function, 41minVal(Variable,Location) power syntax subroutine, 147multi-field runs, 63multicomponent calculation variables, 53multiple-line expressions, 15

Nnamed objects

in CCL syntax, 11

OobjectExists() power syntax subroutine, 147objects

deleting using the command line, 136offset temperature

in CEL, 17operators and built-in functions

CEL, 15Output window overview, 4

Pparallel calculation variables, 53parameter values

in CCL syntax, 11parameters

in CCL syntax, 11

particle tracking variables, 52particle variables

list of all, 64type - boundary vertex, 68type - field, 65type - particle sources into the coupled fluid phase, 65type - radiation, 66type - RMS, 69type - track, 64type - vertex, 66

power syntax, 137examples, 137subroutines, 140

power syntax subroutinesarea(Location,Axis), 141areaAve(Variable,Location,Axis), 142areaInt(Variable,Location,Axis), 142ave(Variable,Location), 142calcTurboVariables(), 142calculate(), 142calculateUnits(), 142compressorPerform(), 142copyFile(), 142count(Location), 143countTrue(), 143cpPolar(), 143evaluate(Expression), 143evaluateInPreferred(Expression), 144exprExists(), 144force(Location,Axis), 144forceNorm(Location,Axis), 144getCCLState(), 144getChildren(), 144getChildrenByCategory(), 144getExprOnLocators(), 145getExprString(), 145getExprVal(), 145getParameterInfo(), 145getParameters(), 145getTempDirectory(), 145getType(), 145getValue(Object Name,Parameter Name), 145getViewArea(), 146isCategory(), 146Length(Location), 146lengthAve(Variable,Location), 146lengthInt(Variable,Location), 146massFlow(Location), 146massFlowAve(Variable,Location), 146massFlowInt(Variable,Location), 147maxVal(Variable,Location), 147minVal(Variable,Location), 147objectExists(), 147probe(Variable,Location), 147range(Variable,Location), 147showPkgs(), 148showSubs(), 148showVars(), 148

169



spawnAsyncProcess(), 148sum(Variable,Location), 148torque(Location,Axis), 148verboseOn(), 148volume(Locator), 149volumeAve(Variable,Location), 149volumeInt(Variable,Locator), 149

printingfrom the command editor, 134

probe function, 42probe(Variable,Location) power syntax subroutine, 147pumpPerform() power syntax subroutine, 147pumpPerformTurbo() power syntax subroutine, 147

Qquantitative calculations

using the command editor, 136

Rradiation calculation variables, 54range(Variable,Location) power syntax subroutine, 147reading state files using the command editor, 132readsession command examples, 131readstate

examples, 133option actions, 133

relational operators, 15reportError() power syntax subroutine, 147reportWarning() power syntax subroutine, 148results file

loading from the command editor, 130rmsAve function, 42rotating frame of reference variables, 52

Ssavestate command examples, 131scalar expressions

CEL, 63session files

reading, 130Show menu overview, 2showPkgs() power syntax subroutine, 148showSubs() power syntax subroutine, 148showVars() power syntax subroutine, 148singleton objects

CCL syntax, 11solid-fluid 1:1 interface

conservative values, 46hybrid values, 46

solid-fluid GGI interfaceconservative values, 46hybrid values, 46

solid-fluid interface variables, 46spawnAsyncProcess() power syntax subroutine, 148state file

reading, 132saving using the command editor, 131

steady-state runs, 62subroutines, 140sum function, 42sum(Variable,Location) power syntax subroutine, 148syntax

case sensitivity in CCL, 10CCL parameters, 11continuation character in CCL, 11end of line comment character in CCL, 10indentation in CCL, 10lists in CCL, 11name objects in CCL, 11parameter values in CCL, 11singleton objects in CCL, 11

system information, 2system variable prefixes, 61system variables

available, 63unavailable, 63

Ttemperature

in CEL expressions, 17temperature variables, 55Toolbar overview, 4Tools menu overview, 3torque function, 43torque(Location,Axis) power syntax subroutine, 148transient runs, 62turbinePerform() power syntax subroutine, 148turbinePerformTurbo() power syntax subroutine, 148Turbo Post

calculating velocity components, 136CCL command actions, 136initializing all turbo components, 136

turbulent flow variables, 49

Uunits

in CEL, 14user level of variables, 47, 64User menu overview, 3

Vvariables

, 109acoustics, 92adaption, 89ANSYS FLUENT field, 79apecies, 84boundary value only, 47, 64Cartesian coordinates, 48cell, 88density, 80derivatives, 91for a rotating frame of reference, 52for buoyant flows, 51



for compressible flows, 51for multicomponent calculations, 53for multiphase calculations, 53for parallel calculations, 53for particle tracking, 52for radiation calculations, 54for total enthalpies, 55for total pressures, 55for total temperatures, 55for turbulent flows, 49granular pressure, 86granular temperature, 86grid, 88grid (turbo), 89hybrid and conservative values, 45list of all, 46long names, 46NOx, 85pdf, 84, 109phase model, 86phases, 86premixed combustion, 84pressure, 80properties, 87radiation, 82reactions, 84residuals, 90short names, 46, 64solid-fluid interface, 46soot, 85temperature, 82turbulence, 83unsteady statistics, 85user level, 47, 64user-defined memory, 88user-defined scalars, 87velocity, 81wall fluxes, 87

variables for CEL Expressions, 55verboseOn() power syntax subroutine, 148volume

function, 43volume(Locator) power syntax subroutine, 149volumeAve function, 43volumeAve(Variable,Location) power syntax subroutine, 149volumeInt function, 44volumeInt(Variable,Locator) power syntax subroutine, 149

Wworking directory selector, 4

171

