493318_trn_2007_cg_cfw2a

COSMOSFloWorks TrainingCOSMOSFloWorks 2007

* 2006 SolidWorks Corp. Confidential.

AgendaCOSMOSFloWorks 2007 CapabilitiesGoverning Equations and Theoretical BackgroundFluid Flow and Heat Transfer TerminologiesLessons and ExercisesQ & A

Agenda


COSMOSFloWorks 2007 CapabilitiesCOSMOSFloWorks is based on advanced Computational Fluid Dynamics (CFD) techniques and allows you to analyze a wide range of complex flows with the following characteristics:Two- and Three-Dimensional analyses External and Internal flowsSteady-state and Transient flowsIncompressible liquid and Compressible gas flows including subsonic, transonic and supersonic regimes


Non-Newtonian liquids (laminar only)Compressible liquids (liquid density is dependent on pressure)Laminar, turbulent, and transitional flowsSwirling flows and Fans Multi-species flows Flows with Heat Transfer within and between fluids and solids (Conjugate Heat Transfer)

COSMOSFloWorks 2007 Capabilities


COSMOSFloWorks 2007 CapabilitiesHeat Transfer in solids only (no fluid exists in the analysis).Surface-to-surface radiation (including solar heating)Flows with Gravitational effects (also known as buoyancy effects) Porous media Fluid flows with liquid droplets or solid particles


COSMOSFloWorks 2007 CapabilitiesWalls with roughnessTangential motion of walls (translation and rotation) Flows in a rotating device (rotating frame of reference)Multiple rotating frames Water vapor condensation Contact resistance Heat sink simulation Fluid subdomains Slip conditionWall simultaneous translation and rotation


COSMOSFloWorks 2007 CapabilitiesNew in COSMOSFloWorks 2007:Cavitation*Thin Wall Mesh Optimization*Relative Humidity*64-bit processors*Orthotropic Material*Thermostat*Thermoelectric Cooler (TEC)**


COSMOSFloWorks Solves the Full Navier-Stokes EquationsConservation equations are conservedConservation of mass (Continuity equation)Newtons second law of motion (Momentum Equation)The first law of thermodynamics (Conservation of energy- Energy Equation)

Governing Equations of Fluid Motion


COSMOSFloWorks solves the governing equations using the finite volume (FV) methodA laminar/turbulent boundary layer model is used to describe flows in near-wall regions. The model is based on the so-called Modified Wall Functions approach.

Theoretical Background


Theoretical BackgroundIterative Methods for Nonsymmetrical ProblemsTo solve the asymmetric systems of linear equations that arise from approximations of momentum, temperature and species equations, a preconditioned generalized conjugate gradient method is used. Incomplete LU factorization is used for preconditioning.Iterative Methods for Symmetric ProblemsTo solve symmetric algebraic problem for pressure-correction, an original double-preconditioned iterative procedure is used. It is based on a specially developed multigrid method


Fluid Flow TerminologyCOSMOSFloWorks always uses absolute pressure. Absolute Pressure - When pressure is given relative to zero pressure (i.e. psia). Gage Pressure - When pressure is given relative to the atmospheric pressure of the surroundings (i.e. psig).For example at sea level the absolute pressure would be 14.6959 psia (pounds per square inch absolute), or 0.00 psig (pounds per square inch gage) if the gage were set to sea level pressure.


Fluid Flow TerminologyThere are two ways to measure pressure in fluid flow: Static Pressure, P, and Total (Stagnation) Pressure, Pt. Static pressure is the pressure indicated by a measuring device moving with the flow or by a device that introduces no velocity change to the flow. The usual method for measuring static pressure in a flow along a wall is to drill a small hole normal to the surface of the wall and connect the opening to a manometer or pressure gage. In the region of the flow away from the wall, static pressure can be measured by introducing a probe, which in effect creates a wall.Total pressure is the pressure measured by bringing the flow to rest isentropically (without loss). A device for measuring total pressure is the Pitot tube, an open-ended tube facing directly into the flow.


Fluid Flow TerminologyDynamic pressure = * Density*Velocity^2 Dynamic pressure can also be defined as the difference between the Total pressure and Static pressure.Ptotal = Pstatic + PdynamicFor compressible flowUsing state adiabatic equation and gas state equation (P=RT) the relation between static and total pressure can be written. From this relation total pressure for gas is determined.


Fluid Flow TerminologyEnvironment pressure BC. Total pressure for incoming flows Static pressure for outgoing flows.

Note: If, during the calculation, a vortex crosses an opening with the Environment pressure condition specified the pressure will be considered as the total pressure at the part of opening through which the flow enters the model and as the static pressure at the part of the opening through which the flow leaves the model.


Laminar, TurbulentLaminar flow:smooth, steady, low speed fluid motion in the form of layers or laminates, little mixing, can be steady-state or transient e.g. lubrication, geometries with small openings, some biomedical Turbulent flow: most engineering problems, agitated, increased mixing and high speed fluid motion with vortices, motion always 3D and transient,solve time-averaged equations for mean flow quantities, mean flow can be steady state or transient in 1D, 2D or 3DExamples: most duct flows, vehicle aerodynamics

Generally characterized by Reynolds number:


Internal and External Flows Internal:flow enclosed by the physical geometryinternal volume typically comprises the analysis volumeExamples: flow in pipes, valves, engines

External:physical geometry is submerged in the fluid Solution domain must be significantly larger than the actual geometry. Analysis typically inverted meaning that the object is held stationary and the liquid is blown over itExamples: wings, missiles, submarines


Exclude internal spaces. Use this option for external flow analyses with closed internal spaces that you wish to exclude from the analysis. Exclude cavities without flow conditions.This option applies to both internal and external flow analyses. The option is useful for closed internal spaces with no Boundary Conditions specified on their surfaces.

Internal and External Flows


Incompressible and Compressible Flow Incompressible: pressure changes do not affect density, pressure disturbances felt everywhere simultaneously, generally lower speed (Mach 0.2Compressible, Ma > 1.0Supersonic Ma > 5.0Hypersonic, disassociation of air molecules, not handled in CFWSubsonic, Supersonic, Hypersonic


Conduction:diffusive transport of energy through solid or fluid via molecular motion

Convection: mass transport of energy through fluid medium via fluid motion

Radiation: electromagnetic wave transport

Conjugate: a combination of 2 or 3 of the above modes Generally solid conduction modeled simultaneously with fluid convection

Modes of Heat Transfer


Newtonian and Non-Newtonian Fluids Newtonian:linear relationship between fluid shear stress and strain through the coefficient of viscosityExamples: most common flows, e.g. air, water, oil, steam

Non-Newtonian: nonlinear relationship between fluid shear stress and strain, viscosity depends upon the strain rate Examples: plastic, blood, rubber, toothpaste


Newtonian and Non-Newtonian Fluids

The following three models of inelastic non-Newtonian viscous liquids are available:

The Herschel-Bulkley modelThe power-law modelThe Carreau model


COSMOSFloWorks is able to treat parts as porous media. Specify the mediums permeability with one of the following four formulas:Pressure Drop, Flow rate, DimensionsDependency on velocityDependency on reference pore sizeDependency on reference pore size and Reynolds numberPorous media


COSMOSFloWorks 2007 Lessons

1 Lids Creation2 Check Geometry 3 Creating a CFW Project4 Meshing and Thin Wall Optimization5 Transient Heat Transfer6 Flow over a cylinder7 Liquid Cold Plate8 Parametric Study Piston Valve

9 Porous Media10 Particle Trajectory11 Supersonic Flow12 Rotating Reference Frame13 Cavitation in a Cone Valve14 Relative Humidity15 FEA Load Transfer -Display

Lesson 1Lid Creation


Lesson 1 TopicsIntroduction to the COSMOSFloWorks interfaceMenus, Toolbars and Icons

This lesson introduces the creation of lids within SolidWorks.

Lids, why are they required?

To perform an internal flow analysis, all openings within a model must be covered using SolidWorks features called "lids. The surfaces of the lids (which contact the fluid) are used to apply boundary conditions which introduce a mass flow rate, volume flow rate, static/total pressure, or Fan condition within a fluid volume.Lids are usually not required for:External analysis problems that measure flow over bodies of geometry such as; cars, planes, buildings, etc.Natural convection problems.

Lesson 2Check GeometryCheck Geometry


Lesson 2 Topics

This lesson introduces the use of the Check Geometry tool which is mainly used to inspect for invalid contacts and to calculate the internal fluid volume within the SolidWorks model.

COSMOSFloWorks divides the SolidWorks model into solid and fluid regions. While meshing the model, COSMOSFloWorks first interprets the specified solid and fluid regions as bodies and then creates a computational mesh for these bodies. The fluid body is created automatically by COSMOSFloWorks and should not be created by the user. Only the solid body is required for the analysis.


Lesson 2 Computational Domain COSMOSFloWorks analyzes the model geometry and automatically generates a Computational Domain in the shape of a rectangular prism enclosing the model. The computational domains boundary planes are orthogonal to the models Global Coordinate System axes.

For External flows, the computational domains boundary planes are automatically distanced from the model capturing the fluid space around the model.

Where as for Internal flows, the computational domains boundary planes automatically envelop the model walls only.


Lesson 2 Check GeometryThe SolidWorks model must be checked to determine if there are any problems with the geometry that may cause problems meshing the body and fluid regions.There are two main reasons that prevent meshing of the solid and fluid bodies: Openings in the geometry that prevent SolidWorks from fully defining a fully closed internal volume. This is for an internal analysis only. Invalid contacts exist between parts in an assembly. An invalid contact is defined as a line or point contact between part files. Invalid contacts affect both internal and external analysis.


Lesson 2 TopicsUpon successful completion of this lesson, you will be able to:Check for invalid contacts.Check the internal fluid volume.


Lesson 2Open AssemblySelect Check Geometry.Check for invalid contacts.Close the Check Geometry tool.Create a section view to identify the invalid contact at the Right Plane, D = 0.0 in.The work around is to change the extrusion type from a Blind extrusion to a MidPlane extrusion. Both Lid 1 and Lid 2 should be modified to a MidPlane extrusion type.Check Geometry for invalid contacts.Save and close the Assembly.


Defining Goals

COSMOSFloWorks initially considers any steady state flow problem as a time-dependent problem. The solver module iterates on an internally determined time step to seek a steady state flow field, so it is necessary to have a criterion for determining that a steady state flow field is obtained, in order to stop the calculations.

COSMOSFloWorks contains built-in criteria to stop the solution process, but it is best to use your own criterion, which are called Goals. You can specify the Goals as physical parameters of interest in the project, so the convergence can be considered as obtaining a steady state solution from the engineering viewpoint. Note that Goals Convergence is one of the conditions for finishing the calculation.


Defining GoalsSpecifying Goals not only prevents possible errors in the calculated values of these parameters, but in most cases also allows you to shorten the total solution time.

You can also monitor the Goals convergence behavior during the calculations, and you can stop the solution process manually if you decide that further calculations are not required.


Defining GoalsYou can set Goals as one of the following four types: Global Goal is a physical parameter calculated within the entire computation domain.Surface Goal is a physical parameter calculated on a user-specified face of the model.Volume Goal is a physical parameter calculated within a user-specified space inside the Computational Domain, either in the fluid or solid (if Heat Transfer in Solids is taken into account).Equation Goal is a goal defined by an equation (basic mathematical functions) with the specified goals as variables . For example: pressure drop,temperature difference, drag, etc.


Defining GoalsYou may specify as many Goals as you wish.

It is often convenient to specify an appropriate goal with the specified condition. For example, if you specify a pressure opening it makes sense to define a mass flow rate surface goal at this opening. COSMOSFloWorks allows you to associate a type of a condition (boundary condition, fan, heat source or radiative surface) with a goal(s), which will be automatically created with the condition if the Create associated goals check box is selected in the conditions dialog box.


Defining GoalsIn the Solver Monitor window the Goal's progress bar is a qualitative and quantitative characteristic of the goal's convergence process. COSMOSFloWorks analyzes the goal's convergence, and calculates the goal's deviation The deviation is defined as the difference between the goal's maximum and minimum values from the last iteration of the analysis interval and the current iteration and compares this deviation with the goal's convergence criterion, either specified by you or automatically determined by COSMOSFloWorks. This deviation is displayed as a fraction of the goal's deviation over the whole computational domain.


Defining GoalsThe percentage of the goal's convergence criterion deviation to the goal's real deviation over the analysis interval is shown in the Solver Monitor window goal's convergence progress bar When the goal's real deviation becomes equal or smaller than the goal's convergence criterion deviation, the progress bar is replaced by word "achieved").


Defining GoalsIf the goal's real deviation oscillates, the progress bar will also oscillate. For some problems, the convergence fraction may regress from an "achieved" level. Therefore, the goal's progress bar together with the goal's convergence history plot are both useful for inspecting the goal's behavior during the calculation, and it does not necessarily indicate when the calculation will finish.


Defining GoalsFor each specified goal you can choose to Use the goal for convergence control or not. Goals that are not used for convergence control will not influence the finish condition, so the calculation may be finished before these goals converge. Such goals are used for information only.


Calculation Control Options Overview

The Calculation Control Options dialog box allows you to specify parameters governing the following COSMOSFloWorks procedures:

Making the decision on when to Finish the calculation. Invoking the refinement of the computational mesh during the calculation sometimes called Solution-Adaptive MeshSaving the results during the calculation.Freezing the flow parameters.Adjusting the time step for a time-dependent analysis. (PE version only)Controlling the number of rays traced from the surface if radiating heat transfer is enabled. (PE version only)


Calculation Control Options - Basic Information

Making the decision for finishing the calculation:For steady-state problems COSMOSFloWorks has default criteria to determine when to stop a solution based on converged results.You can change the default automatic conditions of finishing the calculation and/or specify other conditions, such as Maximum iterations, Maximum CPU time, Maximum travels and others.


Calculation Control Options The End GameFinishing the CalculationUsing the Finish tab you can specify the conditions of stopping the calculation.In the Value cell select either If one is satisfied or If all are satisfied, to automatically stop the calculation if one of the specified conditions is satisfied, or if all the specified conditions are satisfied.


Calculation Control Options The End Game

Finishing the Calculation conditions:Minimum refinement number. Regardless of the selected Finish conditions, the calculation cannot finish until the specified number of refinements is performed during the calculation. Maximum iterations.Maximum physical time (for time-dependent analyses only). Maximum calculation time. The calculation finishes as soon as the specified maximum CPU time is reached.Maximum travels.A Travel is defined as a unit characterizing the calculation duration.The value N travels denotes the calculation period required for a flow disturbance to cross the computational domain N times.


Calculation Control Options The End GameFinishing the Calculation conditions:Goals convergence. The calculation finishes as soon as the specified goals have converged. If there are no goals specified or no goals are taken into account as finishing conditions, the COSMOSFloWorks internal convergence criteria will be used to finish the calculation. Analysis interval (in travels). The interval over which the goals convergence criteria are checked. The analysis interval is reckoned back from the last iteration and indicated by the white bar on the goal plots X-axis if you select Show analysis interval in the Goal Plot Settings dialog box.


Calculation Control Options The End GameGoals criteria. The goals permissible deviation (in the goals units) over the Analysis interval reckoned backward from the current iteration.When the goals deviation over the last iteration becomes lower than the last Analysis interval, the goal is considered as converged. If you clear the On/Off check box for a specific goal, this goal will not influence the task convergence. If you clear the On/Off check box for all specified goals, the task convergence will be only governed by the COSMOSFloWorks internal convergence criteria.


Calculation Control Options The End GameGoals criteriaThe goals deviation cannot be determined automatically before the calculation, so they are not shown in the Auto mode. If you want to use Equation Goals for finishing the calculation, you have to specify their criterion deviation manually in the Value cell. The criterion value is seen in the Criterion column of the Goal Plot dialog box.NOTE: Goals are not checked for their convergence criteria until the calculation has past the minimum number of travels. Depending on the task definition (low or high Mach number gas flow, etc.) the minimum number of travels can equal any value between 0.5 and 1 travels.



RefinementRefining the computational mesh during the calculation to obtain more accurate results, it is expedient to adapt the computational mesh to the solution (in other words, to refine the mesh) in the course of the calculation. Under some conditions, COSMOSFloWorks does this by default, but to intensify (or relax) this process, you can change its default settings.SavingBy default, COSMOSFloWorks saves the final calculation results only. If you need a time succession of calculation results for a time-dependent problem or, e.g., want to save the intermediate results in view of a possible abnormal termination of the calculation, you can specify the time moments for saving the results during the calculation



AdvancedFreezing (i.e. taking from the previous iteration) values of all flow parameters, with the exception of the fluid and solid temperatures and fluid substance concentrations (if several substances are considered). Sometimes it is necessary to solve a problem dealing with different processes developing at substantially different rates. If the rates difference is substantial (10 or more times) then the CPU time required to solve the problem is governed by the slowest process. To reduce the CPU time, a reasonable approach is to stop (freeze) the calculation of the process that has fully developed and does not change further and use its results to continue the calculation of the slower processes.



AdvancedManual Time Step - specifying a problems physical time step for time-dependent analyses. By default, the time step used to solve time-dependent fluid flow problems is specified by COSMOSFloWorks automatically, based on the fluid flow properties. If you want to either better resolve a problems time-dependent solution (by specifying a smaller time step than the automatically selected one, e.g. for resolving periodic solutions of very small periods) or to calculate a heat transfer in solids faster (by specifying a larger time step than the automatically selected one, e.g. if the fluid flow does not change), it is sometimes better to expedient the analysis by specifying the time step manually.Radiation - controlling the number of rays traced from a surface in case a heat transfer analysis with radiation is solved.

Lesson 3Creating a COSMOSFloWorks Project


Lesson 3 Topics and stepsThis lesson covers the flow of air through a manifold assembly. The objective is to introduce the set up of a COSMOSFloWorks project within SolidWorks.Open AssemblyCreate a project using a wizard.Create a New Project.Select Units; SI (m-kg-s)Select fluid type (Gas or liquid). Set the fluid type to Gas.Setting Analysis Type. Set the Analysis type to Internal.Choose the fluid (Gas) properties. Choose Air under the database of fluids.Click Next accepting the default definitionsSetting Automatic Initial Mesh. Accept the default Result Resolution setting of 3.Click on Finish


Lesson 3 Topics and stepsInsert Boundary Condition.- Inlet ; Volume flow rate normal to face = 0.05 m^3/s.- Outlet boundary conditions ; Static Pressure, option default ambient valuesEngineering goals - Surface Goal ; Inlet SG Volume Flow Rate.- Repeat the previous step to apply a Surface Goal for the Volume Flow Rate for each of the 6 outlets- Insert Equation Goal. Add the Outlet SG Volume Flow RateSolve the CFW project. The solver should take approximately 30 minutes to run on a 2 GHz P4 platform.

Delphine Genouvrier - The Inlet volume goal is set just so that the student has an Inlet value to compare to when the equation goal is used to add the outlet volume flow rates. There is no other reason


Key Results Create Cut Plots. Create Surface Plot. Create Flow Trajectory. (16 trajectories) Plot XY Plot.In this lesson we will plot the pressure and velocity along the manifold. Choose Velocity and Pressure under the list of parameters.


Key Results Create Surface Parameters. Calculate the average static pressure drop from the valve inlet to outlet.

Save and close the assembly file.

Lesson 4Meshing and Thin Wall Optimization


The Mesh

COSMOSFloWorks automatically generates a computational mesh.You can specify parameters governing the initial computational mesh. The mesh is named initial since it can be later refined during the calculation (Solution-Adaptive Meshing).The mesh is created by dividing the computational domain into slices, which are further subdivided into rectangular cells. Then the mesh cells are refined as necessary to properly resolve the model geometry.


The MeshFloWorks leaves the SolidWorks solid model as it is - as solidsEmploys an intelligent, fully automatic, adaptive grid generation procedureAutomatic meshAutomatic solution adaptive mesh adaptation during solution


FloWorks Mesh Cell TypesFluid cells entirely in fluid regionSolid Cells entirely in solid regionPartial cells cells that contain both fluid and solid regions which help define the fluid/solid interfaceIrregular cells are partial cells that can not properly define the fluid-solid interface.


Computational MeshAutomatic unstructured Cartesian mesh with local refinements Result Resolution 1-5Automatic solution adaptive mesh algorithm (fine and extra-fine resolution only)Result Resolution 6-8


Useful tools to control Mesh and componentsResult ResolutionGeometry ResolutionSolution-Adaptive MeshComputational DomainComponent Control


Result Resolution


Result ResolutionGoverns the solution accuracy through mesh settings and conditions of finishing the calculation that can be interpreted as resolution of calculation results. You specify result resolution in accordance with the desired solution accuracy, available CPU time and computer memory. Because this setting has an influence on the number of generated mesh cells, a more accurate solution requires longer CPU time and more computer memory.


Result ResolutionUsing the slider, you can select one of the eight resolution levels. The first level will give the fastest results but the level of accuracy may be poor. The eighth level will give the most accurate results but may take a long time to converge. Increase result resolution level if you want to improve the quality of the results.

For the majority of tasks you can achieve stable results starting from level three. However, some types of tasks require increasing the result resolution level (e.g. external flows with separation from smooth surfaces).


Result ResolutionStart with a low resolution and increase resolution if necessary You can use lower Result Resolution settings as initial conditions for high Result Resolution settings.

Sheet1

GOALS

Design CriteriaGlobal GoalSurface GoalVolume Goal

Pressure Drop or LossPres.P(inlet), P(outlet)

EfficiencyPres.

Drag

Structural IntegrityForceForceForce

Surface FinishShear Force

Temperature LimitationTemp.Temp.

Fluid MixingConcentrationConcentration (in/out)

Flow VisualizationPres., Temp., Conc.

Sheet2

BOUNDARY CONDITIONS

InletOutlet

Internal/Incompressible

Sheet3

Result ResolutionApplications

Settings 1-3h The first calculation of a new problem

h "What-if" studies

Setting 4 or 5h Final calculation

Setting 6, 7, or 8h Most precise

h Academic studies


Geometry Resolution

COSMOSFloWorks calculates the default minimum gap size and minimum wall thickness using information about the overall model dimensions, the Computational Domain, and faces on which you specify Conditions and Goals. This information may be insufficient to recognize relatively small gaps and thin model walls. This may cause inaccurate results. In these cases, the Minimum gap size and Minimum wall thickness must be specified manually.


Geometry ResolutionAllows you to specify the Minimum gap size and Minimum wall thickness to discern diminutive geometry that is not automatically recognized by COSMOSFloWorks. These settings have an influence on a characteristic cells size and together with Result Resolution govern the total number of cells generated in the computational mesh.


Geometry ResolutionPrior to starting the calculation, we recommend that you check the geometry resolution to ensure that small features will be recognized. Use FloWorks, Project, Summary to observe the Minimum gap size and the Minimum wall thickness. If you set boundary conditions, surface goals, or modify the model or computational domain, these characteristic sizes may change. Click FloWorks, Project, Rebuild to update the minimum gap size and minimum wall thickness.


Geometry ResolutionIn case of internal analyses, boundaries between internal flow and ambient space are always resolved properly because COSMOSFloWorks distinguishes the internal flow volume and ambient space. If your model does not contain walls with both sides contacting the fluid and it does not contain thin features protruding into the fluid, then the Minimum wall thickness value should not be changed.The manually specified values are retained if you modify the model or COSMOSFloWorks project.If you specify very small values for these reference sizes and a high result resolution, the number of mesh cells will dramatically increase, resulting in increases in memory requirements and CPU time.


Minimum gap sizeThe automatically generated minimum gap size depends on the model size, computational domain, volume sources, initial conditions, and boundary conditions. If the model has a gap which is smaller than the Minimum gap size, then the gap can be not considered during the calculation (e.g., fluid will not pass through the gap or the gap can become smaller or greater).


Minimum gap sizeYou can link the minimum gap size value to a feature or reference dimension so that the minimum gap size value will be equal to the dimension. Changing the dimension value causes the minimum gap size value to change.


Minimum wall thicknessThe automatically generated minimum wall thickness value depends on the model size, computational domain, volume sources, initial conditions, surface sources and surface goals. The Minimum wall thickness does not influence the meshing if it is equal to or greater than the Minimum gap sizeIf the model wall or solid protrusions thickness are less than the Minimum wall thickness and Minimum gap size, then the solid walls (with both sides contacting the fluid) will not be resolved properly during the calculation (i.e., the solid will be replaced with fluid).


Minimum wall thicknessYou can link the minimum wall thickness value to a feature or reference dimension so that the minimum wall thickness value will be equal to the dimension. Changing the dimension value causes the minimum wall thickness value to change.


Min Gap Size (MGZ) & Min Wall Thickness (MWT)H = 2.75MWT = 0.125MGZ = 0.182L = 10.25W = 6.25


Computational MeshThe Basic mesh (left) and the Initial mesh (right).


Computational Mesh Basic MeshThe computational mesh is rectangular everywhere in the computational domain, so the mesh cells sides are orthogonal to the specified Cartesian coordinate systems axes and are not fitted to the solid/fluid interface.First a basic mesh is constructed. For that, the computational domain is divided into slices by the basic meshs planes, which are evidently orthogonal to the Cartesian coordinate systems axes.

The basic mesh is governed by the computational domain only and does not depend on the solid/fluid interfaces.


Computational Mesh Initial MeshCapture the solid/fluid interface - The basic meshs cells, cut by the solid/fluid interface are split uniformly into smaller cells

Each of the basic meshs cells, cut by the solid/fluid interface, is split uniformly into daughter cells until the specified cell size is attained for the result resolution specified.


Initial MeshRefinement PrinciplesRefinement Level from 0 to 8The difference in refinement level for neighbor cells in not more then 1


Computational Mesh Initial meshThe solid/fluid interface curvature If the angle between the normals dropped from the neighboring daughter cells centers to the solid/fluid interface exceeds the criterions value, each of these daughter cells is split further, whereas if this angle is less than the criterions value, all daughter cells are merged into the parental cell.


SolidWorks Modeling Tips to Reduce the Mesh

Simplify the model by suppressing unimportant features with SW or using Component Control in COSMOSFloWorksAvoid small gaps, cavities, or clearancesAlign your model wrt the global co-ordinate systemTo troubleshoot problems use the COSMOSFloWorks Check Geometry command & SW Cavity command


Which pipe model would you expect to contain the most cells in the mesh?Pipe A10 inch Diameter, 10 inches long straight pipePipe B1 inch Diameter, 10 inches long straight pipePipe C1 inch Diameter, 10 inches arc length, 90 degree bend pipe (same fluid volume as Pipe B)


Pipe A10 inch Diameter, 10 inches long straight pipePipe B1 inch Diameter, 10 inches long straight pipe

Pipe C1 inch Diameter, 90 degree bend pipe (same fluid volume as Pipe B)

Which pipe model would you expect to contain the most cells in the mesh?


Which pipe model would you expect to contain the most cells in the mesh?

Fluid volumeIn^3 Aspect ratio (length/diameter)Number of Cells, Default Settings in FloWorksStraight pipe, 10 inch diameter, 10 inch long78511,000

Straight pipe 1 inch diameter, 10 inch long7.85104,656

90 deg. sweep pipe 1 inch diameter, 10 inch long7.85106,162


COSMOSFloWorks MeshIn general geometries with large aspect ratios (ratio of largest geometric dimension to smallest gap or thinnest wall) are very time consuming to mesh and solve. This is a common issue with any CFD (computational fluid dynamic) software. The problem is aggravated even further if there is sweep or curvature.


Solution-Adaptive Meshing Basic Information Since all the above-mentioned meshing procedures are performed before the calculation, the obtained mesh is unable to resolve all the solution features well.The solution-adaptive meshing is a procedure for adapting the computational mesh to the solution during the calculation. It involves splitting the mesh cells in the high-gradient flow regions and solid regions, which cannot be resolved prior to the calculation or during the previous solution-adaptive mesh refinements and merging the mesh cells in the low-gradient regions. COSMOSFloWorks allows you to change the values of the parameters governing the default solution-adaptive meshing procedures.


Solution-Adaptive MeshingGeometry refined mesh Solution Adaptive Mesh


Optimize thin walls resolution The optimize thin wall option should be checked whenever a flow model contains thin walls (walls with fluid on both sides). This option improves the meshing of thin wall features and in many cases reduce the overall number of cells required to mesh thin wall features. If unchecked, additional mesh refinement will be required to properly resolve thin wall features, but the refinement will cause a large increase in the number of cells in the model, especially in the narrow channels between the walls.


Optimize thin walls resolutionThe Optimize thin walls resolution option resolves thin wall features without any manual refining of the mesh around the thin wall features because both sides of the thin wall can reside within the same cell. The amount of cells needed to resolve a thin wall is generally lower in most cases than the number of cells needed to properly resolve a wall of the same width. Cells in the thin wall regions contain more than one fluid and/or solid volume. During the calculation, each such volume has an individual set of parameters depending on its type (fluid or solid).


Lesson 4 Meshing ExerciseUpon successful completion of this lesson, you will be able to:Generate proper mesh in the presence of thin walls and narrow channels.Use mesh features.Display mesh.Use Thin wall optimization feature.


Lesson 4 Optimize thin walls ExerciseA part with several very thin baffles has water flowing through it. Theobjective is to find the velocity profile and the flow trajectories.


Optimize thin walls resolution

Lesson 5Transient Heat TransferTransient Heat Transfer


Lesson 5 Topics and steps - Transient Heat TransferThe objective of this lesson is to introduce the set up of a time dependent heat transfer problem within COSMOSFloWorks.Open AssemblyCreate a New Material/Material, SolidsCreate a Project.


Lesson 5 Topics and steps - Transient Heat Transfer


Lesson 5 Topics and steps - Transient Heat TransferDefine Custom Unit System.Units/Load/USA/OK.Changing Units ; change the Length unit to in, Change the units for Total heat flow & power to W.Save button. Unit System name = USA w/inches & Watts.

Apply Inlet Boundary Conditions. Volume flow rate normal to face = 0.15 ft^3/sApply Outlet Boundary Condition. Static pressure = ambient pressure


Lesson 5 Topics and steps - Transient Heat TransferApply Heat Source. Chip/Heat Generation Rate/Dependency typeFor the other three chips, modify the time points for each chip heat load so that the heat is applied at different intervals.


Lesson 5 Topics and steps - Transient Heat TransferDefine Material Conditions for Chip; Chip Material.Define Material Conditions for Top Cover, Bottom Cover and Enclosure; Aluminum. Define Engineering Goal (Volume Goal); Temperature of Solid/Avg for each chipSolve the FloWorks project.


Orthotropic material (Optional exercise)


Orthotropic material (optional)Electronic chip maintained 100 C. Two (upper and lower) flow paths. The lower flow path has room temperature air (20 C) blowing on the chip at 5 m/s. The upper flow path has colder (5 C) air blowing over the heat sink at 5 m/s.Materials used to manufacture the chip and the middle plate have orthotropic conductivity properties.The objective of this analysis is to obtain the distribution of temperature in both the chip and the middle plate.


Orthotropic material (optional)


Orthotropic material

Materials with orthotropic thermal conductivity (optional)

Lesson 6Flow over a Cylinder


Lesson 6 Topics

The objective of this lesson is to introduce the 2D Plane flow option.At low Reynolds numbers (4 < Re < 60) two steady vortices are formed on the rear side of the cylinder and remain attached to the cylinder, as shown below schematically. At higher Reynolds numbers the flow becomes unstable and a von Karman vortex street appears in the wake past the cylinder.


Lesson 6 Steps


Lesson 6 StepsSet Computational Domain.Boundary Condition = XY- Plane Flow

Define Engineering Goal. Global Goal/X - Component of ForceDefine second Engineering Goal. Global Goal/Y- Component of ForceDefine Equation Goal (Drag Coefficient) : Run the FloWorks project.

Lesson 7Liquid Cold PlateLiquid Cold Plate


Lesson 7 Topics -Liquid Cold Plate-This lesson covers the flow of water through a heated liquid cold plate located in an open air filled environment. The objective is to introduce the set up of a conjugate heat transfer analysis using multiple fluid domains.Water InletWater Outlet


Lesson 7 Steps - Liquid Cold Plate


Lesson 7 Steps - Liquid Cold Plate


Lesson 7 Steps - Liquid Cold PlateInlet boundary conditions. - Inlet Mass Flow/normal to face/0.5 kg/sOutlet boundary conditions. - Static PressureHeat Source. - Heat Generation Rate = 2000 W on top surface of the Cold Plate


Exercise 1: Heat Exchanger with Multiple Fluids

A copper heat exchanger is used to transfer heat between air and water systems. 450 K of hot air is entering the heat exchanger (at the inlet indicated in the figure) at a rate of 0.15 kg/s. Water is pushed through the heat exchanger at a rate of 0.1 kg/s. The objective of this exercise is to obtain the temperature profile in both media.





Lesson 8Parametric Study Piston Valve


Lesson 8 Topics Parametric Study - Piston Valve

The objective of this lesson is to introduce the following concepts:Create an analysis using the Parametric (optimization) Study feature.Create a quarter model using symmetry planes.


Lesson 8 Parametric Study - Piston Valve

Lesson 9Porous MediaPorous Media


Lesson 9 -Porous MediaThe objective of this lesson is to introduce the following concepts:Create a flow analysis using the porous media option.Apply a non-uniform inlet velocity boundary condition.Use the Component Control command.


Lesson 9 -Porous MediaCold air flow is forced through a porous screen within a channel. At the channel inlet the velocity profile is a function of the inlet height.

Example description with non-uniform inlet velocity profileThe channel height is 0.15 m, the channel length is 0.65 m, the porous screen thickness is 0.01 m. All walls have a thickness of 0.01 m.


Lesson 9 Steps -Porous MediaXY Plane Flow : 2D plane flow


Lesson 9 Steps -Porous MediaBoundary Condition - Variable inlet Velocity Dependency type ; F(y) - table


Lesson 9 Steps -Porous MediaOutlet boundary conditions. Pressure openings ; Static Pressure.Porous Media.- Engineering Database.User Defined: Porosity = 0.5. Permeability type = Isotropic. Resistance calculation formula = Dependency on velocity. A = 57 kg/m^4. B = 0.- Disable the Porous media component- Apply the Porous conditionSet Engineering Goals.- Surface Goal/Av/Static Pressure on the inlet faceRun the FloWorks project.

Lesson 10Particle TrajectoryParticle Trajectory


Lesson 10 Topics -Particle Trajectory

The objective of this lesson is to introduce the injection of a physical particle into a uniform flow stream.Particle trajectories are calculated in the postprocessor after completing a fluid flow calculation. Assumption; Particle motions and temperatures have a negligible influence on the fluid flow parameters. Particles are treated as non-rotating spheres of constant mass and specified material.This lesson will analyze the perpendicular injection of a particle into an incoming uniform flow. To simplify the analysis this problem will be solved as a 2D (i.e. in the XY-plane) flow problem.


Lesson 10 Steps -Particle Trajectory

XY- Plane Flow = 2Dplane flow



Inlet velocity boundary condition. - Velocity Normal to face = 0.6 m/s.Outlet boundary conditions. - Pressure openings. Static PressureIdeal walls

Engineering Goals. Surface Goal/Av/Static Pressure/inlet face

Run the FloWorks project.



Create Flow Trajectories- Particle Study. Injection type = Table. Add the points 0, 0, 0. Settings. Velocity Condition = Absolute. - Particle Material Value = Iron - Particle Study Boundary Condition = Absorption. - Physical Models. Y-Gravity = -9.8 m/s



You can try the following three cases: Air flow with Vinlet = 0.002 m/s, gold particles of d = 0.5 mm,injected at the velocity of 0.002 m/s perpendicularly to the wall. Water flow with Vinlet = 10 m/s, iron particles of d = 1 cm, injectedat the velocities of 1, 2, 3 m/s perpendicularly to the wall. A particle trajectory in the Y-directed gravitational field(gravitational acceleration gy = -9.8 m/s2, air flow with Vinlet = 0.6m/s, an iron particle of d = 1 cm, injected at the 1.34 m/s velocity atthe angle of 63.44o with the wall).

Lesson 11Supersonic flowSupersonic flow of air overa segmental conic body


Lesson 11 Topics -Supersonic flow of air over a segmental conic body

The objective of this lesson is to introduce the following concepts:Create an external supersonic flow analysis.Use the solution adaptive mesh feature for supersonic flows.Create contour plots of Mach number.


Lesson 11 Topics -Supersonic flow of air over a segmental conic body

Lesson 12Multiple FluidsRotating Reference Frame


Lesson 12 Topics - Rotating Reference Frame The objective of this lesson is to demonstrate the set up of a Rotating Reference Frame option.


Lesson 12 Topics - Rotating Reference Frame

Lesson 13FEA load transfer DisplayCavitation in a Cone Valve


Lesson 13 Topics -Cavitation in a Cone Valve

The objective of this lesson is to introduce the cavitation flow type option.


Lesson 13 Topics -Cavitation in a Cone Valve

Cavitation in a Cone Valve

Lesson 14FEA load transfer DisplayRelative Humidity


Lesson 14 Topics -Relative Humidity

The objective of this lesson is to introduce the following concepts:Applying Relative Humidity as a boundary conditionDisplaying Relative Humidity results


Lesson 14 -Relative Humidity

Cavitation in a Cone Valve

Lesson 15FEA load transfer DisplayFEA Load Transfer -Display Board


Lesson 15 Topics -FEA Load Transfer Display Board

The objective of this lesson is to introduce the following concepts: Transfer flow results to COSMOSWorks for a finite element analysis.Create a COSMOSWorks study using results from FloWorks as input boundary conditions.View results in COSMOSWorks.


Lesson 15 Topics -FEA Load Transfer Display Board


Some Q & A


Issues - 1CFD is best for comparing two or more designsCautious while taking absolute numbersNo Written Standard or Specification document (unlike in Structural Mechanics where you have standards from ASME or ASCE) In structural mechanics you can look at the Factor Safety and say the design is good or not. But in CFD, you cannot come up with such one number. You have to compare with the test dataDifficulty in comparing with test dataExpensive to perform testing for CFDMeasurement of pressure, velocities, temperature in experiments is prone to errorsHow much can I trust the result for the given Mesh No error estimate (unlike in Structural Mechanics where you can get a plot of error estimate for energy)Check Mesh Convergence (Result Resolution 3, 4, 5..)


Issues - 2Review verification problems for practiceAbout a dozen problems with FloWorks project set up alreadyCheck your FloWorks installation folder


CompatibilityCOSMOSFloWorks 2007 works only with SolidWorks 2007.


Import fluid flow results from CFW into COSMOSWorksYou can export Fluid flow results from COSMOSFloWorks PE version to COSMOSWorks to conduct a design analysis.The following COSMOSFloWorks quantities can be imported into COSMOSWorks:Static pressure on solid surfaces; Heat transfer coefficient and reference temperature; Solid bodies temperature. Tips and Tricks before importing the results to COSMOSWorks:

Suppress all lid features used for boundary conditions from the SolidWorks feature manager tree.

By unchecking COSMOSFloWorks from the SolidWorks Tools Add-Ins list, you can avoid receiving messages asking whether to modify the computational domain and mesh settings.

Save the model. You must save the model each time you export results. When you perform exporting results, no physical export file is created, but the model itself is modified.


Reference temperatureh = q/(Tfluid - Twall)Allows you to manually specify an appropriate reference fluid temperature for visualizing the heat transfer coefficient alpha:, where q is the heat flux from the wall to the fluid, calculated by COSMOSFloWorks, Twall is the wall temperature calculated by COSMOSFloWorks, Tf is the user-specified Reference fluid temperature.------------------------------------------------------------The Reference fluid temperature is required by the user to calculate the heat transfer coefficient.Once the user specifies the Reference fluid temperature the user can then display the heat transfer coefficient in the Cut plot, XYPlot, Point Parameter, ..etc commands.Because there are different types of fluid temperatures used to calculate the heat transfer coefficient. Sometimes users want to calculate the local heat transfer coefficient which uses the local ambient fluid temperature, other users may want to calculate a average heat transfer coefficient which would require an average fluid temperature. Sometimes users use the film temperature, Tfluid = (Tsurface + Tambient)/2.The fluid temperature not only varies in the axial direction but also the normal direction of the surface. Just like there is a velocity gradient near the wall there is also a corresponding thermal gradient. The fluid molecule right next to the wall is much hotter then the fluid molecule near the free stream. Depending on what the users wants will determine which fluid temperature is used to calculate the heat transfer coefficient. So there is no one fluid temperature, that's why this value is a user defined value. It gives the user more choices.


ParticlesOnly spherical particles are consideredParticles do not influence the flow carrying themRadiation from particles is not taken into accountNo local settings for absorption/reflection condition


GoalsSurface goal; what is the difference between 'Average value' and 'value' ?

The 'Average Value' of a Surface Goal is the average value calculated over the Analysis Interval (averaged over several interations of the calculation). The 'Value' is the current iteration value for the Surface Goal


Appendix : resultsSurface parametersFor example cooling water flowing through a pipe with heated walls may appear hotter if the average value is used compared to the Bulk average for the water temperature. The water near the pipe walls is hotter then the centerline fluid temperature. If the flow rate is high the Bulk average is a better average for the fluid temperature.


Appendix : flow files.cpt - binary file, contains the mesh information. You need to keep this file to restart the analysis without remeshing..cpt.stdout - ASCII text file, contains summary data about the meshing process..fld - binary file, contains the results for viewing. If you ever want to look at the results again keep this file..fwp - binary file, contains the setup information for the COSMOS/FloWorks project. This includes the settings made through the wizard as well as boundary conditions, heat sources, volume conditions, goals, etc. Definitely keep this file..stdout - ASCII text file, summary file of the solution (similar to an .OUT file).r_00000*.fld - binary file, contains the data necessary for a solution restart. So if you want to run more iterations and start from where the solution previously finished, you need to keep this file.

Slide is self explanatory

NOTE:Typical applications: weve added a great number of slides on typical applications. Please use only the appropriate slides for the specific customer. The equations are supplemented by fluid state equations defining the nature of the fluid, and by empirical laws for the dependency of viscosity and thermal conductivity on other flow parameters

Transport equations are used for the turbulent kinetic energy and dissipation rate (k- e model)

on a spatially rectangular computational mesh designed in the Cartesian coordinate system With the planes orthogonal to its axes and refined locally at the solid/fluid interface and, if necessary, additionally in specified fluid regions, at the solid/solid surfaces, and in the fluid region during calculation. Values of all the physical variables are stored at the mesh cell centers. the governing equations are discretized in a conservative form. The spatial derivatives are approximated with implicit difference operators of second-order accuracy. The time derivatives are approximated with an implicit first-order Euler scheme.This model is employed to characterize laminar and turbulent flows near the walls, and to describe transitions from laminar to turbulent flow and vice versa.

Both procedures do not affect the model but allow you to avoid unnecessary mesh refinements and flow calculations in non-analyzed model regions There is a difference between Exclude internal Spaces and Exclude cavities without flow conditions. The Exclude internal Spaces is meant for External flow type problems and it forces FloWorks to ignore all internal spaces. The Exclude cavities without flow conditions is meant for internal type flow problems and allows FloWorks to only ignore cavities that do not have boundary conditions. You need both commands. For example lets say you have an internal valve analysis that contains voids. You want FloWorks to ignore these voids but not to ignore the main pipe flow volume that contains boundary conditions. The Exclude internal Spaces would ignore the whole pipe flow analysis. So the Exclude cavities without flow conditions would work best. The Exclude internal Spaces is really for external analysis which can analyze both internal and external flow analysis at the same time The compressible liquid equations are different from the compressible gas equations. Compressible gas equations use the Perfect Gas Law which can not be used for a compressible liquid. Depending on how much over Mach 5 you go the solver will probably continue to run and even converge on an answer. Unfortunately the answer may not be accurate. There is no magic number but at speeds around Mach 5 the air molecules around an object heat up because of friction and begin to dissociate. The fluid equations used for computational fluid dynamics begin to break down because the gaseous species are undergoing chemical reaction or dissociation. As temperature of a diatomic or polyatomic gas such as oxygen or nitrogen is raised above 2000 R the bonds holding the molecule together loosen and, at higher temperatures break. The molecule is then split, or dissociated, into constituent atoms. At still higher temperatures, the atoms themselves break down into positively charged ions and negatively charged electrons.

COSMOSFloWorks is capable of calculating the laminar flow of inelastic non-Newtonian liquids. All available non-Newtonian models are based on the assumption that the flows shear stress () is a function of the flows shear rate ().The computational domain for external flow analysis is dependent on the geometry and flow conditions. There is no magic ratio for setting the computational domain for external flow analysis. It is important that the user captures all of the flow gradients around the geometry and downstream of the geometry. The upstream dimension is not as important. Typically the user must run the external flow analysis with a estimated computational domain and then reset the dimensions of the computational domain based on the results if needed. The Result Resolution is a measure of the desired level of accuracy of the results. It controls not only the resolution of the mesh, but also setsmany parameters for the solver, e.g. the convergence criteria. The higher the Result Resolution, the finer the mesh, which usually meanshigher total cell counts and increased physical RAM.The Inlet volume goal is set just so that the student has an Inlet value to compare to when the equation goal is used to add the outlet volume flow rates. Erratum ; in the manual, they speak about the graph of the Total pressure whereas the graph shows the Static pressureThe sketch used for the XYPlot can be drawn either before or after the run.Basically the Bulk value is a "weighted" average and the Average value is an area only average. Please notice that the Bulk average has density in the Bulk equation and the Average value does not have density.The 'Average Value' of a Surface Goal is the average value calculated over the Analysis Interval (averaged over several interations of the calculation). The 'Value' is the current iteration value for the Surface Goal. FloWorks was exclusively developed to be integrated into SolidWorks. There is no stand-alone version available, nor does FloWorks support any other solid modeling package. This focus on a single modeling environment gives the user full access to all the capabilities of SolidWorks without any compromise. Historically, fluid flow simulation software was developed for use on workstation computers running under a UNIX operating system, or on mainframe computers. While those codes have been ported to PCs they still carry a significant amount of legacy issues from the mainframe and UNIX days. FloWorks is the first fluid simulation software that was exclusively designed for use on PCs under the Windows operating system. This allows FloWorks to benefit from all the advantages of modern technology without the need to consider old program parts or backward compatibility. You have to find an answer to a physical engineering question. This engineering analysis goal is the basis for the whole simulation process within FloWorks. You don't need to know about numerical convergence criteria values, iteration numbers, relaxation factors, etc. But you know what you want to achieve, which turnaround time you can accept and which computing resources you can provide. FloWorks will do its best to give high quality answers within these conditions. This unique technology enables design engineers to access and to take advantage of a powerful design tool. A main component of what makes FloWorks, what it is, is our Intelligent Driver Interface or IDI.

-The discussion for the turbulent intensity can be very complex. But I will try to describe it in a few lines.It is convenient to think of turbulent flows as being composed of two parts, mean and fluctuating. The mean quantity can be obtained by an appropriate averaging procedure. The fluctuating quantity can be obtained by the variance (or the standard deviation) which is used to estimate the variability of the turbulent fluctuations of the flow. Turbulent intensity is defined as the fluctuating part of the velocity (standard deviation) divided by the free stream velocity. The value is then multiplied by 100 and displayed as a percentage. The turbulent intensity can only be determined experimentally. Note: The length of the cylinder is 0.001 m. The fluid analysis length is the Z thickness of the computational domain not the actual length of the cylinder.The Porosity is defined as the total fluid volume divided by the total volume of the porous media. So a value of 0.5 means that 50% of theporous media is fluid.The medium permeability is independent of direction within the mediumk = (AV+B)/r (named Dependency on velocity), where V is the fluid velocity and r is fluid density, A and B are constants. Youspecify A [kg/m^4] and B [kg/(sm^3)] only (V and r are calculated).Usually these values are supplied by the porous media manufacturer.

The Ideal Wall condition allows you to apply adiabatic, frictionless wall boundary conditions instead of the default fluid friction wall. If appropriate, you can also use the Ideal Wall condition to introduce a flow symmetry plane, which can assist in reducing the computational resources. The top and bottom walls are set to Ideal Walls so that the trajectory of the particle is not influenced by wall frictional effects. The intend is to show a nice projectile type trajectory path. The frictional wall effects may effect the path of the particle. The Ideal Wall condition is not required for the particle trajectory command. It was just used for effect Particle Study Boundary Condition tabThis menu allows the user to specify what happens if the particle comes in contact with a wall. For this lesson we will keep the default wallcondition to Absorption which means if the particle(s) come in contact with a wall the particle will be absorbed by that wall. The other optionsallow for reflection of the particle after contact with the wall.

The Absorption option causes the particle to stick to the wall as soon as it makes contact. Yes, 0 K is very low. For this analysis, the temperature does not affect the results. You can make the temperature any value you like. The default value is 0 K so we left it at the default temperature.

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