flow around a cylinder - hs-augsburg.dethalhof/downloads/tmgfflow.pdf3 setup what: open the tutorial...
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1TMGFtut93a
Flow Around a CylinderFEMAP TMG Flow Tutorials
Learn how to:
• mesh for the fluid analysis• define fans and vents• solve the fluid analysis• post process the results
An optional part at the end shows how to:• model a heat load and convection.
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Before you begin...
Software requirements:
1. Demo License or TMG Flow*
2. Your FEMAP installation must includeParasolid capabilities
*The optional section requires a Demo License, orTMG Flow and TMG Thermal Licenses.
Prerequisite tutorials:
1. Getting Started (FEMAP Training Examples)
Note: If these tutorials are not available at yourinstallation, you can still complete this tutorial if youhave someone show you how to start the software anduse the menus and mouse.
Recommended tutorials:
1. Groups, Layers, Viewing and Post Processing
2. Simple Solid
Completed sample modelAfter you finish the tutorial, you can compare yourmodel with a sample model. This sample was createdusing the techniques described in this workshop andshould match your model perfectly.The sample is stored as:.../tmg/doc/femap/tutorials/cylinde_solved.MOD (thefirst part of the path may vary slightly depending onyour FEMAP installation).
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Setup
What: Open the tutorial model file.How:Start FEMAP and load the model:...\tmg\doc\femap\tutorials\cylinder_meshed.MOD(the first part of the path may vary slightly dependingon your FEMAP installation).What: Save a copy of the model.Recovery Point
File > Save As [save the file to a localdirectory]
Open
By default, there are no units in FEMAP. You mustmake sure that the geometry dimensions areconsistent with the unit system of the materialproperties and boundary conditions that will apply tothe model. All dimensions specified in this tutorialare in meters.
Things to notice With TMG, you can specify whetheryour model is unitless (default), in Standard units, or inUser Defined units. For this first tutorial, we will leavethe default option on.
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Modeling Overview 1 of 4
Modeling OverviewThe model consists of a rectangular air duct with acylinder cutting across it.
FRONT VIEW
Air enters from one end of the tunnel and exits at theother end, flowing around the cylinder.The inlet and outlet are modeled by defining boundaryconditions on both surfaces at the ends of the tunnel.
ISOMETRIC VIEW
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Modeling Overview 2 of 4
The model has already been air meshed in order tohave less than 300 nodes for FEMAP Demo Licensecompatibility.If you have the TMG Flow License and want greateraccuracy, you can delete the existing mesh and createa much finer one.The 3D fluid elements within the geometry define thevolume of air.The cylinder is not meshed. To model the effect of anobstruction, simply leave the volume of the obstructionunmeshed.
Unmeshed volume
Unmeshed Volume Deflects the Flow
Schematic3D air mesh
Unmeshed surfaces are automatically defined asdefault smooth walls by TMG Flow.
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Modeling Overview 3 of 4
Openings such as fans and vents are typically definedon a surface that forms part of a solid meshed with3–D fluid elements. The 3–D fluid elements (solidelements with fluid properties) represent the fluidvolume. One or more of the surfaces defining the fluidvolume can define the extent of the boundarycondition.During the solve, the boundary condition informationon the surface is transferred to the 3–D element faces.
Free faces of 3–D fluid elements (schematic)
surface
Things to notice The surface must be coplanar with the 3D elementfaces underneath it.
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Modeling Overview 4 of 4
Check the material properties for the air elements.
Entity Selection – Select Material(s) to Edit form
Select All
OK
Define Fluid Material formThings to notice
• Air is the only material defined in the model.• Material properties are defined using SI units.• You must use a fluid material to be able to solve
with TMG Flow.
Cancel
Save your model.Recovery Point
File > Save
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Part 2: Defining and Solving the TMG Model
In this part of the tutorial, you will:• create the fan and vent boundary conditions• specify the Run Directory, Ambient Conditions
and Solver Control• solve• check the solution
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Define and solve the TMG model 1 of 9
What: Open the TMG panel.
TMG Panel
Things to notice The TMG panel is used for both TMGand TMG Flow. Your license controls the access tosome icons.What: Activate the Flow Panel View option .TMG Panel > Options > Icon Panel Views
Flow (toggle on)
Create an Inlet Fan with a velocity of 0.1 m/s.
Fan
Create Fan form
Name: Inlet
Element Selection: Faces of volumeelem. on surface
Pick...
Entity Selection formSelect the left end surface of the volume.
OK
Fan Type: Inlet
Flow Parameter: Velocity
Velocity: 0.1
OK
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Define and solve the TMG model 2 of 9
What: Create a Vent.
Vent
Create Vent form
Name: Vent
Element Selection: Faces of volumeelem. on surface
Pick...
Entity Selection formSelect the right end of the volume.
OK
Create Vent formThings to notice For this model, we will accept the
default Vent to ambient option. The TMG Vent entitymodels an opening that allows fluid to enter or leavethe fluid domain. You do not specify a vent as being aninlet or an outlet. It is the flow distribution that willdetermine whether fluid is exiting or entering the modelthrough the vent.
OK
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Define and solve the TMG model 3 of 9
It’s good practice to check the boundary conditionsin the model before solving. The TMG ModelManager gives a clear overview of all the boundaryconditions, and provides easy access if you need tochange any values or selections.
What: Start the TMG Model Manager.How:Click on any icon. At the very bottom of the listthat appears, you have two special buttons: Manager...and Dismiss. Pick the Manager... button.
TMG Model Manager formThings to notice
The main panel of the form displays a list of all theentity types in the model.
Fans (double click)
Inlet (click)
Sketch geomThings to notice
The graphics window displays the surface you selectedwhen you defined the thermal coupling.
Redisplay
Inlet (double click)
Fan – Modify formCheck the values in the fields, and make anymodifcations required.
OK
Check the Vent in this way as well.
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Define and solve the TMG model 4 of 9
Specify a Run DirectoryWhy:Many files are created during the solve. Thesefiles always use the same name. Specifying a RunDirectory facilitates file management and prevents thefiles from being overwritten.
FE Study
FE Study form
Run Directory
Run Directory: cylinder\
The backslash ( “\” ) is required. TMG will create therun directory (if it does not already exist) in thedirectory from which FEMAP was launched.
Things to notice Review the form. The two boundary conditions youcreated are Active in the default FE study.
Do not close the form! In the coming pages you willuse the icons on this form to specify the AmbientConditions and the Solver Controls.
Why:The icons on the FE Study form are also on theTMG panel, but sometimes it is easier to use themfrom the form.
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Define and solve the TMG model 5 of 9
Define the Ambient Conditions.Why:These conditions apply to the air outside of thefan and vent. In particular this defines the pressure justoutside of the vent.
Ambient Conditions (icon on form)
Ambients Conditions formThings to notice
In the unitless mode, some values are negative bydefault. This ensures that these required fields arefilled in.
Static Pressure: 101351 (Pa)
Gravitational Acceleration: 9.81 (m2/s)
OK
Things to notice Gravitational acceleration is not used in this model butit must be specified.
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Define and solve the TMG model 6 of 9
What: Set the Solver Controls.
Solver Control (icon on form)
Solver Control form
Execute Thermal Solver (toggle off)Why:We are only interested in executing the flowsolver.
OK
Close the Study Setup form.
OK
Boundary conditions and Solver Control are defined.You are ready to solve. Save your model beforecontinuing.Recovery Point
File > Save
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Define and solve the TMG model 7 of 9
Solve the model.
Solve
If your Run Directory does not exist, a warningmessage appears asking your permission to create it.Pick Yes.
Things to notice When you launch a solve, FEMAP is frozen and theSolver Monitor appears a few seconds later.
Errors, warnings, and information are displayed in themessage window. Use the scroll bar to scan thesemessages. (All data in this window can be reviewedlater by selecting the View All Messages icon on theTMG panel.)
The Stop button will terminate processing and deleteall intermediate results. Pause suspends the thermal orflow solution and recovers results for post-processing.Even if the solution has not converged, this featurepermits you to inspect the results after a few iterations.
Examine the progress of the solution on the followingpages.
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Define and solve the TMG model 8 of 9
Examine the solution in progress.
Flow
Things to notice You may examine the Flow Solution monitor at anytime during the solve. This display is updatedautomatically and will graphically show how close youare to the convergence criterion (horizontal line at1E-03).Residuals for the X,Y, and Z velocity (U,V, and Wmomentum), and mass are plotted. Turbulent kineticenergy and dissipation rate are only displayed if the KETurbulence Model is active.
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Define and solve the TMG model 9 of 9
Once the solve is done, review the solver messages ineither the Solution Monitor window or with View AllMessages icon.
Things to notice • Scroll to the bottom of the window and check the
Solver Convergence Summary. Imbalances formass and momentum are provided. Normally,these imbalances should be smaller than 1% forthe solution to be considered converged.
• A detailed summary for mass and momentum isgiven just after the last solver iteration.
• At the end of the file, just before the SolverConvergence summary, you will find the SolutionSummary. Check this summary to see maximumand minimum fluid velocities and otherinformation about the results.
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Part 3: Post Process the Results
In this part of the tutorial, you will:• post process velocities and pressure• use dynamic cutting plane
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Post proces the results 1 of 5
What: Import the results.
Get Results
What: Close the TMG Panel:
File > Exit
Why:All post processing functionality is availablewithin FEMAP, not TMG.
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Post process the results 2 of 5
Display the air velocities.View Select
View Select form
Vector
Deformed and Contour Data...
Select PostProcessing Data form
Contour: VELOCITY AT ELEMS TWhy:The Output Set contains the magnitude of thevelocity vector at each node. You will use a postprocessing option to color the vectors with the contourselection later.
Contour Vectors...
Contour Vector Options form
3D Components
Vector 1: VELOCITY AT ELEMS X
Vector 1: VELOCITY AT ELEMS Y
Vector 1: VELOCITY AT ELEMS ZThings to notice The velocities must be specified in the
same column. The other columns are ignored.
OK (all forms)
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Post process the results 3 of 5
Color the velocities with the contour selection.View > Options...
View Options form
Category: PostProcessing
Options: Contour Vector Style
Color Mode: Contour Colors
Options: Contour/Criteria Levels
Level Mode: Auto – Group
OK
Things to notice Colors now refer to the color bar.
Zoom in to better see the flow around the cylinder. Youcan also rotate the model.
Use Ctrl–A to resize the graphic.
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Post process the results 4 of 5
Display an isometric view of the model.View > Rotate > Model...
View Rotate form
Isometric
OK
Display the total pressure.View Select
View Select form
Contour
Deformed and Contour Data...
Select PostProcessing Data form
Contour: TOTAL PRESS AT NODES
OK (all forms)
Things to notice Pressure is displayed on the outersurfaces of the volume.
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Post process the results 5 of 5
Display the pressure on a cutting plane.View > Advanced Post > Dynamic Cutting Plane...
Dynamic Section Cut Control form
Plane...
Plane Locate - Define Primary Cutting Plane form
Methods: Global Plane
Base X: 0
Base Y: 0
Base Z: 0
XY Plane
OK
Dynamic Section Cut Control form
Move the cutting plane with the scrollbar on the form.
Close the form.
Cancel
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Wrap up
If you have a TMG Thermal License, you can continueto the next optional section. Otherwise, this is the endof this tutorial.Be sure to save your work before exiting FEMAP.Recovery Point
File > Save
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Optional: Adding a Thermal BoundaryCondition
In this part of the tutorial, you will:• create the required material and property• mesh the cylinder surface• define a heat load and flow surface for the
cylinder• solve and post process the results
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Add a Thermal Boundary Condition 1 of 12
Display the model as a wireframe.
Wireframe
Turn off the display of nodes and elements
Quick Options
View Quick Options form
All Entities Off
Geometry On
Done
Display the entire model.
Model Data...
Select Model Data for View form
Group: None
OK
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Add a Thermal Boundary Condition 2 of 12
What: Create a material to be used on the cylinder.
Model Info
Model
Materials (Right–click, select New)
Define Isotropic Material form
Type...
Material Type form
Isometric
OK
Define Isotropic Material form
Title: Cylinder Material
Conductivity, k: 45
OK
Cancel
What: Create a plate property for the cylinder thermalboundary condition elements.
Model Info
Model
Properties (Right–click, select New)
Define Property –* Element Type form
Element / Property Type...
Element Property Type form
Plate
OK
Define Property – PLATE Element Type form
Title: Cylinder Prop
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Thickness, Tavg or T1: 0.001
Material: Cylinder Material
OK
Cancel
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Add a Thermal Boundary Condition 3 of 12
Mesh the cylinder surface.
Surface
Entity Selection – Select Surfaces to Mesh formPick the 2 surfaces as shown in red:
OK
Automesh Surfaces form
Property: Cylinder Prop
OK
Save your model.Recovery Point
File > Save
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Add a Thermal Boundary Condition 4 of 12
Check the mesh for coincident nodes and coincidentelements.
Coincedent Nodes
Entity Selection - Select Node(s) to Check form
Select All
OK
Check/Merge Coincident form
Merge Coincident Entities
OK
Check for coincident elements.
Coincedent Elements
Entity Selection - Select Element(s) to Check form
Select All
OK
Check Coincident Elements form
(Toggle OFF all Check Options.)
OK
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Add a Thermal Boundary Condition 5 of 12
What: Open the TMG panel.
TMG Panel
What: Define a heat load of 100W on the cylinder.
Thermal B.C.
Create Thermal BC form
Name: Cylinder 100 W
Element Selection: Plane elements onsurface
Pick...Pick the 2 surfaces as shown in red:
OK
Type: Total Heat Load
Constant: 100
OK
1
2
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Add a Thermal Boundary Condition 6 of 12
Define a Surface Property characterizing the cylinderroughness. Use a roughness value of 0.0 in. to modelsmooth surfaces.
Surface Property
Create Surface Properties form
Name: Smooth
Use surface roughness of
Use surface roughness of: 0.0
OK
Define a Flow Surface for the cylinder.
Why:Flow Surfaces (and Blockages) are the entitiesthat can convect to the fluid.
Flow Surface
Create Flow Surface form
Name: Cylinder Surface
Element Selection: Plane elements onsurface
1 2 (pick two cylindrical surfaces)
Pick...
OK
Recovery PointFile > Save
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Add a Thermal Boundary Condition 7 of 12
Specify a new Run Directory
FE Study
FE Study form
Run Directory: thermal\
Activate the Thermal Solver.
Solver Control
Solver Control form
Execute Thermal Solver
OK
Close the FE Study form.
OK
Boundary conditions and solver controls are nowdefined. You are ready to solve. Save your modelbefore continuing.Recovery Point
File > Save
1
2
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Add a Thermal Boundary Condition 8 of 12
What: Create groups for the cylinder elements and thefluid volume.Group > Set...
Create or Activate Group form
Title: Cylinder
OK
Group > Element > on Surface
1 2 (pick two cylindrical surfaces)
OK
Group > Set...
Create or Activate Group form
ID: 2
Title: Air
OK
Group > Element > in Solid / Volume
Enter Curve To Select Elements for Group form
Select All
OK
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Add a Thermal Boundary Condition 9 of 12
What: Solve the model.
Solve
What: Import the results.
Get Results
What: Close the TMG Panel
File > Exit
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Add a Thermal Boundary Condition 10 of 12
Display the temperatures on the cylinder.View Select
View Select form
Contour
Deformed and Contour Data...
Select PostProcessing Data form
Output Set: Thermal Steady StateWhy:The Thermal Steady State output set containsthe solid (non–fluid) element results.
Contour: Plate Top ELEM TEMP
Contour Options...
Select Contour Options form
Elemental
No AveragingWhy:For a coarse mesh, averaged results can bemisleading.
OK (all forms)
Continued on next page..
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Add a Thermal Boundary Condition 11 of 12
Display the cylinder.
Model Data...
Select Model Data for View form
Group: Select
Group: Cylinder
OK
Things to notice The cylinder is colder in the regionswhere the flow is faster.
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Add a Thermal Boundary Condition 12 of 12
Display the temperature of the fluid.View Select
View Select form
Deformed and Contour Data...
Select PostProcessing Data form
Output Set: 2..Flow Steady StateWhy:The second Flow Steady State output set wascreated during the second solve and contains the fluidtemperature.
Contour: FLUID TEMP AT NODES
OK (all forms)
Things to notice The hotter regions correspond to theareas where the flow is the slowest.
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Wrap up
This is the end of this tutorial.Be sure to save your work before exiting FEMAP.Recovery Point
File > Save