openfoam introduction - uliege · openfoam what's openfoam? openfoam: open source field...

OpenFOAMIntroduction

Speakers:Francois Rigo

Francois.Rigo@student.ulg.ac.be

José Rothkegelji.rothkegel@ulg.ac.be

Amandine GUISSARTamandine.guissart@ulg.ac.be

February 2016

OpenFoam

What's OpenFOAM? OpenFOAM: Open source Field Operation And

Manipulation C++ toolbox for the development of customized

numerical solvers, and pre-/post-processing utilitiesfor the solution of continuum mechanics problems,including computational fluid dynamics (CFD).

OpenFoam

What comes with OpenFOAM? Basic CFD solvers

Incompressible flow with RANS and LES Advanced CFD solvers

Compressible flow solvers with RANS and LES Buoyancy-driven flow solvers Multiphase flow solvers Combustion problems Solvers for conjugate heat transfer

Particle Tracking

Molecular dynamics solvers[28]

Electromagnetics solvers

Solid dynamics solvers

OpenFoam

What are the applications of OpenFOAM?

CATIA Room

Ubuntu Login User: foam Pass: catia1135

Linux Basics

Open Terminal: In gnome 2.x:

Applications → Accesories → Terminal In KDE 4.x:

Applications menu → Systems → Konsole

Linux Basics

Create Folder ~$mkdir name

Copy files ~$cp name destination

Delete files(attention: no undelete option) ~$rm name

Rename file ~$mv name_original name_new

To edit a file, we'll use Gedit $gedit filename

Linux Basics

Change directory ~$cd folder

Go to home directory ~$cd

See working directory ~$pwd

See working directory's content ~$ls

OpenFOAM Basics

Create a directory named student_work_2016_A in the OpenFOAM workdirectory

~$cd

~$cd OpenFOAM/foam-2.1.1/run

Note: you can use the <tab> key to autocomplete the line ~$mkdir student_work_2016_A

Copy the cavity problem to the created directory ~$cp -r tutorials/incompressible/icoFoam/cavity student_work_2016_A/

Go to student_work_2016_A ~$cd student_work_2016_A

Rename the folder to Cavity_original ~$mv cavity cavity_original

Go to cavity_original folder ~$cd cavity_original

OpenFOAM Basics

Folder structure

OpenFOAM Basics

Test case problem: lid-driven cavity

OpenFOAM Basics

Block Structure of of mesh

OpenFOAM Basics

blockMeshDictconvertToMeters 0.1;

vertices ( (0 0 0) (1 0 0) (1 1 0) (0 1 0) (0 0 0.1) (1 0 0.1) (1 1 0.1) (0 1 0.1));

OpenFOAM Basics

blockMeshDictblocks ( hex (0 1 2 3 4 5 6 7) (20 20 1) simpleGrading (1 1 1));

OpenFOAM Basics

blockMeshDictboundary( movingWall { type wall; faces ( (3 7 6 2) ); }

fixedWalls { type wall; faces ( (0 4 7 3) (2 6 5 1) (1 5 4 0) ); }

...

...

frontAndBack { type empty; faces ( (0 3 2 1) (4 5 6 7) ); });

OpenFOAM Basics

To generate the mesh from the blockMeshDict: ~$blockMesh

To visualize the mesh: ~$paraFoam

OpenFOAM Basics

In paraFoam:a) Apply in the Object Inspector

b) Surface With edges in the representation menu

a

b

OpenFOAM Basics

Problem set-up Initial values: Folder ”0”

U p

Properties: Folder ”constant” TransportProperties

Numerical Control: Folder ”system” controlDict fvSchemes fvSolution

OpenFOAM Basics

File: ”p”dimensions [0 2 -2 0 0 0 0];

internalField uniform 0;

boundaryField{ movingWall { type zeroGradient; }

fixedWalls { type zeroGradient; }

frontAndBack { type empty; }}

OpenFOAM Basics

File: ”U”dimensions [0 1 -1 0 0 0 0];internalField uniform (0 0 0);boundaryField{ movingWall { type fixedValue; value uniform (1 0 0); }

fixedWalls { type fixedValue; value uniform (0 0 0); }

frontAndBack { type empty; }}

OpenFOAM Basics

File: ”U” For external flows

dimensions [0 1 -1 0 0 0 0];internalField uniform (0 0 0);boundaryField{ dummyWall { type freestream; freestreamValue uniform (1 0 0); }

}

OpenFOAM Basics

File: ”transportProperties”nu [ 0 2 -1 0 0 0 0 ] 0.01;

OpenFOAM Basics

File: ”controlDict”application icoFoam;

startFrom startTime;startTime 0;stopAt endTime;endTime 0.5;

DeltaT 0.005; // CFL is imposed through δt

writeControl timeStep;writeInterval 20;purgeWrite 0;writeFormat ascii;writePrecision 6;writeCompression off;

timeFormat general;timePrecision 6;runTimeModifiable true;

CFL=δ t|U|δ x

OpenFOAM Basics

To run the case ~$icoFoam

To visualize the results: ~$paraFoam

paraFoam Basics

a

paraFoam Basics

b

c d

paraFoam Basics

Common toolbar

Glyph: to show arrows

Stream tracer: to showstreamlines

Student Work

Mesh Grading Problem is based on the lid-driven cavity tutorial It introduces the mesh grading feature

Student Work

Test case problem: lid-driven cavity

Student Work

Student Work

Create a directory named student_work_2016_A in theOpenFOAM work directory

~$cd

~$cd OpenFOAM/foam-2.1.1/run

Note: you can use the <tab> key to autocomplete the line Copy the cavity problem to the created directory

~$cp -rtutorials/incompressible/icoFoam/cavitystudent_work_2016_A/

Go to student_work_2016_A

~$cd student_work_2016_A/

Rename the folder to cavity_grading

~$mv cavity cavity_grading

Student Work

blockMeshDictvertices( (0.0 0.0 0.0) (0.5 0.0 0.0) (1.0 0.0 0.0)

(0.0 0.5 0.0) (0.5 0.5 0.0) (1.0 0.5 0.0)

(0.0 1.0 0.0) (0.5 1.0 0.0) (1.0 1.0 0.0)

(0.0 0.0 0.1) (0.5 0.0 0.1) (1.0 0.0 0.1) (0.0 0.5 0.1) (0.5 0.5 0.1) (1.0 0.5 0.1) (0.0 1.0 0.1) (0.5 1.0 0.1) (1.0 1.0 0.1));

Student Work

blockMeshDictblocks( hex (0 1 4 3 9 10 13 12) (10 10 1) simpleGrading (2 2 1) hex (1 2 5 4 10 11 14 13) (10 10 1) simpleGrading (0.5 2 1) hex (3 4 7 6 12 13 16 15) (10 10 1) simpleGrading (2 0.5 1) hex (4 5 8 7 13 14 17 16) (10 10 1) simpleGrading (0.5 0.5 1));

Student Workboundary( movingWall { type wall; faces ( (6 15 16 7) (7 16 17 8) ); }

fixedWalls { type wall; faces ( (3 12 15 6) (0 9 12 3) (0 1 10 9) (1 2 11 10) (2 5 14 11) (5 8 17 14) ); }...

...

frontAndBack { type empty; faces ( (0 3 4 1) (1 4 5 2) (3 6 7 4) (4 7 8 5) (9 10 13 12) (10 11 14 13) (12 13 16 15) (13 14 17 16) ); });

Student Work

Build mesh ~$blockMesh

Run the files: ~$icoFoam

View the results: ~$paraFoam

OpenFOAM Integrals

To calculate the integral of variable over apatch

General structure ~$ patchIntegrate <variable> <patch>

For example: ~$ patchIntegrate U movingWall

OpenFOAM Integrals

To calculate forces controlDict...timeFormat general;

timePrecision 6;

runTimeModifiable true;

functions{

#include "forceCoeffs"}

OpenFOAM Integrals

To calculate forces forceCoeffs Adapted from

tutorials/incompressible/simpleFoam/motorBike/system/forceCoeffs

/*--------------------------------*- C++ -*----------------------------------*\| ========= | || \\ / F ield | OpenFOAM: The Open Source CFD Toolbox || \\ / O peration | Version: v3.0+ || \\ / A nd | Web: www.OpenFOAM.com || \\/ M anipulation | |\*---------------------------------------------------------------------------*/

forceCoeffs1{ type forceCoeffs;

functionObjectLibs ( "libforces.so" );

outputControl timeStep; timeInterval 1;

log yes;

patches ( patchesName ); rhoName rhoInf; // Indicates incompressible rhoInf 1; // Redundant for incompressible liftDir (0 0 1); dragDir (1 0 0); CofR (1 0 0); // Axle midpoint on ground pitchAxis (0 1 0); magUInf 20; lRef 1.0; // Reference length Aref 1.0; // Reference Area}

Remember to set the correct values!!!

C L=2FL

ρU∞2 A

CD=2FD

ρU∞2 A

References

Linux Just google:”linux commands”

OpenFOAM OpenFoam User Guide

Installing OpenFOAM http://www.openfoam.com/version-v3.0+/