ffc v5.0 08 fluent solution

1-1ANSYS, Inc. Proprietary© 2009 ANSYS, Inc. All rights reserved.

February 17, 2009Inventory #002702

Introduction to FLUENT for CATIA V5

FLUENT Solution Process and Setup



Training Manual

FLUENT for CATIA V5 Version 5.0Introductory Training, December 2009

Fluent for Catia Support center http://www.fluentusers.com/ffc

Agenda

• FLUENT Problem Setup• FLUENT Solver Parameters• Solver Accuracy• Monitoring the Solution• Setting Solution Monitors• Residual and Solution

Monitors• Cavitation Monitors• Running the Fluent

Calculation• Remote Submission on

LINUX/Windows clusters• FLUENT Computation

Control

• Managing Multiple CATIA Sessions

• Multiple Boundary Condition Sets

• Journal Customization• Batch Mode Computing• Creating Local Sensors• Appendix

– Solver Accuracy Slider Bar Settings

– User-supplied BAT and JOU files



Training Manual



• To finalize the FLUENT problem setup in the specification tree, double click on the Fluent Problem Setup.1 in the specification tree to open the subsets:

– Unsteady parameters: only appears when the problem setup is unsteady

– Journal customization: pre, post or full fluent journal files can be input

– Monitor convergence criteria: opens up the dialog box on the right

FLUENT Problem Setup



Training Manual



• FLUENT Problem Setup – Operating conditions: opens the

operating conditions box– Initialization values: for

initialization of the solution field– Reference values: sets up

reference values for calculating normalized quantities (frequently in the post-processing stage) or dimensionless parameters

FLUENT Problem Setup



Training Manual



• FLUENT solver parameters can be adjusted by the FFC user.

• Double click on Fluent Solution under Fluent case in the specification tree to open up the Fluent Solution box.

• The panel allows users to:– Set Solver Accuracy Settings– Set Residual Convergence

Criteria– If convergence criteria is none,

then the Residual Convergence Criteria is grayed out (as shown)

– Set Under-relaxation settings– Enable Solution Steering and

Polyhedral Conversion– Set the number of parallel

processes– Set Maximum CPU Time or Max

number of iterations.

FLUENT Solver Parameters



Training Manual



• Solution accuracy is specified using a slider bar in the Fluent Solution menu.

– Setting “1” on the left yields a first cut solution.

– Settings 3,4 and 5 yield a high accuracy solution.

– Please see Appendix for detailed information.

• The Customization tab in Tools Options menu has an option to control the accuracy based on the position of Mesh Definition.

Solver Accuracy



Training Manual



• The residuals are the primary mechanism to monitor solution progress.

– Residuals represent the imbalance in the equations being solved by FLUENT.

• When the values of the residuals decreases below the convergence criteria set in the Fluent Solution panel, the computation stops.

• Additional Flux balance and average based convergence criteria can be selected in the Tools Options menu.

• Solution Monitors can also be created to provide a check on progress of the solution.

Monitoring the Solution



Training Manual



• Solution Monitors provide an additional check on solution progress.

– If the solution monitors are still changing when the residuals have converged, the solution is not complete.

• The solution monitors include:– Force Monitor: Drag, Lift and

Moment– Surface Monitor: Average, Minimum

and Maximum of flow variables on surface

– Center Pressure Report

• Right click on the Monitors.x under the Fluent case in the specification tree and select the monitor.

Setting Solution Monitors



Training Manual



• In the monitor panel– Specify the face group(s) where

the monitor is calculated in “Supports”.

– Set the report file path– The physical quantity to be

calculated.

• Characteristic scales like length, area, and temperature, etc. should be set up in Reference Values.x for calculating non-dimensional coefficients.

Setting Solution Monitors



Training Manual



• Residual plots and Monitor plots are shown in addition to normal Fluent Solution progression window.

Residual and Solution Monitors



Training Manual



• When Cavitation/VOF is activated in the Problem Physics panel, an additional “Phase Input” button is added to the Residual Convergence panel.

– Click on the button and set the residual for the phase input panel.

Cavitation and VOF Monitors



Training Manual



Running the Fluent Calculation• Once the case setup is complete,

mesh generation and solution calculation is carried out using the Compute panel.

• The Compute panel has two sections.

• In the first section, the user can choose among a number of options:

– All: Create mesh and run solution

– Mesh Only: create mesh– Surface Mesh Only: create

surface mesh– Volume Mesh Only: create

volume mesh– Analysis Case Solution

Selection: Select Fluent Case for computation.



Training Manual



Running the Fluent Calculation• In the second section, the user can

select among the following options:– Default Solution Options:

Calculation based on settings defined in the Tools Options dialog box

– Run Computation: start the Fluent calculation, if the mesh is ready.

– Continue Computation: continue the calculation from the point where it was interrupted.

• Pre-iteration journal– Write Case File Only: create a

FLUENT case file– Attach Data File Only: attach a

FLUENT data file– Initialize Only: Initialize the data field

for visualization.



Training Manual



Running the Fluent Calculation• The progression of the solution

calculation is shown in a pop-up window with a progress bar and values of the scaled residuals and/or fluxes.

• Additional windows show plots of residuals and solution monitors.



Training Manual



FLUENT Computation Control

• The FLUENT Computation Control panel allows you to:

– Control one or more solutions running in batch mode

– Attach data files from another fluent run to the present solution

– Start the solution monitor in the Fluent Calculations Progression dialog box

• The panel can be used to manage multiple runs in batch mode by using the following functions:

– Attach data file– Refresh all– Stop computation– Start monitor



Training Manual



• The storage manager can be used to manage files for multiple cases/sessions.

Managing Multiple CATIA Sessions



Training Manual



Multiple Boundary Condition Sets

• Multiple boundary condition sets can be easily set up and computed for the same case:

– Set up a first case, FFC generates Boundary Conditions.1 under the Fluent case set in the specification tree

– Insert a new case by clicking on the Insert Fluent Case icon.

– Click OK on the Fluent Case panel to create a new Fluent case set in the specification tree.

– Set the Boundary Conditions for the new Fluent case.

– In the Compute panel, select Analysis Case Solution Selection from the top list, then select the Solution to be computed.



Training Manual



• Journal Customization:– Pre-Iteration Journal: Modify

case setup done by FLUENT for CATIA.

• e.g. change turbulence model or discretization schemes.

– Post-Iteration Journal: Perform specific post-processing after the solution is done.

– Full Journal: • Useful in batch mode• Should contain all the

commands to iterate the solution

• When this is enabled, Pre and Post-Iteration journal options will be turned OFF.

Journal Customization



Training Manual



• Batch mode computing is more convenient for larger and longer simulations

• Enable Compute in Batch Mode in Fluent Solution dialog box, click OK.

• Click on to open Compute dialog box, select appropriate choices and launch solution iterations.

• A warning will be displayed to inform you the job is running in the batch (background) mode.

• Upon completion, you must attach the Fluent data file from the lower list of the Compute box in order to post-process the completed batch solution.

Batch Mode Computing



Training Manual



Creating Local Sensors

• A local sensor in CFD computation provides output of physical quantities of interest during the iteration process

• Right click on the Sensor.1 in the specification tree under Fluent case and select Create local senor in the contextual menu.

• In the local sensor dialog box, specify location, the type of phyiscal quantity to be computed.

• FLUENT for CATIA can use local sensors which are combined with CATIA’s product engineering optimizer (PEO) to obtain CFD-based optimization.



Training Manual



Launching FLUENT• FLUENT can be launched from FLUENT for CATIA using the buttons

on the Fluent toolbar.– The FLUENT button first saves the case/data files used by FLUENT to a

specified directory before launching FLUENT. (requires license)– The last button gives the version number for FLUENT for CATIA.



Appendix



Training Manual



Solver Accuracy Slider Bar Settings• The Solver Accuracy Slider Bar can be set to one of five values: 1, 2,

3, 4, 5.– Slider bar setting 1, has the highest speed and lowest accuracy.– Setting 5, has the lowest speed and highest accuracy.

• It controls the numerical discretization used in the CFD calculation for different flow variables:

– First order discretization is simple and has low accuracy but is fast.– Second order discretization is complex and is accurate but takes more

time.– First order is used for preliminary calculations on a coarse mesh.– Second order is used for more accurate calculations on a finer mesh or

tet/hybrid mesh.

• The table in the next slide shows the discretization schemes for different variables for each slider bar settings.



Training Manual



Slider Bar for Solution Accuracy

Slider Position

Pressure Density Momentum Energy k Epsilon/Omega

Reynolds Stresses

1 Standard First-Order

First-Order First-Order

First-Order

First-Order

First-Order


First-Order First-Order

First-Order

First-Order

First-Order


First-Order Second-Order

First-Order

First-Order

First-Order


Second-Order

Second-Order

Second-Order

First-Order

First-Order


Second-Order

Second-Order

Second-Order

Second-Order

First-Order



Training Manual



• The user-supplied batch and journal files should be located in the directory specified in File for batch computation box inside the Toolsoptions dialog box

• The batch file (here it is called batch.bat ) must be a script performs at least the following steps:

– Read the directory in which FFC case file is stored

– Create a lock file– Start the fluent solver using a journal

file – A sample batch file is shown on the

right

User-supplied BAT and JOU files

<> echo off%1

cd %2echo >> %3

fluent 3d –hidden –wait –i yourJournal.jou



Training Manual



User-supplied BAT and JOU files• The journal file must perform at

least the following steps:– Read in the case file– Iterate– Write out the case/data files – Delete the lock file generated for this

process– Send out a notification to inform

FFC users that the run is completed• A simple sample journal file called

yourJournal.jou is included for a reference

rc yourFFCcase.cas/so in in

/so it 1000/f bf n

wd yourFFCdata.dat/f bf n

wc yourFFCcase_1.cas(system “del yourFFCcase.lok”)

(system “echo >>yourFFCcaseisdone”)(exit)

yourJournal.jou

ffc v5.0 08 fluent solution

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