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Old   April 1, 2010, 03:06
Default maxCo or whatever..
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nikita tryaskin
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Under running project by pisoFoam i got really big(first steps) Courant number
but if you see in controlDict i have maxCo = 0.5

////////////////////////////////////////////////////////////////////////////////////
...........................
Create time

Create mesh for time = 0

Reading field p

Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting turbulence model type LESModel
Selecting LES turbulence model Smagorinsky

Starting time loop

Time = 0.001

Courant Number mean: 0.305251 max: 4.50564
//////////////////////////////////////////////////////////////////////////////////////////////

Next - solver thinks a lot and unconvincing compute..
Courant number growth like Godzilla.. lol
second iteration and it is more than 80.000

Could it be so problem with dimensions? or much possible with boundary conditions or mesh?
checkMesh says that my Mesh is Ok...


Ниже ControlDict:


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.6 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application pisoFoam;

startFrom latestTime;

startTime 0;

stopAt endTime;

endTime 10;

deltaT 0.001;

writeControl adjustableRunTime;

writeInterval 0.5;

purgeWrite 0;

writeFormat ascii;

writePrecision 6;

writeCompression uncompressed;

timeFormat general;

timePrecision 6;

runTimeModifiable yes;

adjustTimeStep yes;


maxCo 0.5;

maxDeltaT 1;

/*
functions
(
forces
{
type forces;
functionObjectLibs ("libforces.so");
patches (walls);
rhoInf 1.225;
CofR (0.15 0 0);
outputControl timeStep;
outputInterval 20;
}
);
*/
// ************************************************** *********************** //
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Old   April 1, 2010, 03:30
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Vojtech Betak
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pisoFoam hasn't a possibility to change a time step. You must set fixed value of deltaT. Another option is to improve a source code of pisoFoam or to use a pimpleFoam
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Old   April 1, 2010, 03:36
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nikita tryaskin
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i have it fixed.. according to ControlDict

btw i have 3d model, have only u, nuSgs and p b.conditions
i need to solve it by LES model, so what can u say about solver i should use.. am i 100% right with pisoFoam?
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Old   July 7, 2014, 09:26
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Tony
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Hi,

I am facing the same problem. Could you please give me a hint on how to make adjustable time step possible in pisoFoam?

Thank you very much.

Best regards,
Tony
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Old   July 7, 2014, 09:50
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Alexey Matveichev
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Hi,

the easiest way is to use pimpleFoam. If you'd like this solver to operate in PISO mode, set number of outer correctors to 1:

$FOAM_SRC/finiteVolume/cfdTools/general/solutionControl/pimpleControl/pimpleControl.C:
Code:
    if (nCorrPIMPLE_ > 1)
    {
        ...    
    }
    else
    {
        Info<< nl << algorithmName_ << ": Operating solver in PISO mode" << nl
            << endl;
    }
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Old   July 7, 2014, 09:59
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Tony
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Thank you very much!

Tony
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