[alexeym]

Hi,

Originally Posted by stephie

The only thing, which did not work is pyFoamPlotRunner.py. There is still the mistake command not found. Maybe I miss something when I installed OpenFoam...do you have any idea?

Well, the reason for behaviour: the folder where utilities are located is not in your PATH variable. Why it is not in your PATH? I do not know. As there are lots of ways to install PyFoam (https://openfoamwiki.net/index.php/C...m#Installation), I can not suggest anything till you tell me how you have installed PyFoam.

I have just checked installation with pip (pip install --user PyFoam) and everything works fine (well, at least pyFoamRunner.py, pyFoamPlotRunner.py fails as I do not have gnuplot installed), utilities are installed and accessible.

[SUBHANKAR]

Hello foamers,
I am solving flow past a cylinder(2-D) for blockage ratio=0.2, Re=300 with parabolic inlet velocity profile. I am getting very high Cd(~2.4). previously i had simulated for blockage ratio=0.3, and Re=100. There i got Cd nearly equal to the literature(~1.35). I used the same case file for the 1st case except changing the blockMesh to get blockage ratio=0.2 and the velocity magnitude to get Re=300. What am i doing wrong? I have taken upstream length=12.5D and downstream length=30D. I have attached my case file.
regards
Subhankar

[albet]

Sorry for the post. The problem was probably the bad installation. The pimpleFoam wasn't able to see the omegaWallFunction, therefore it switched automatically to zeroGradient on the wall, and gave me bad results in foam-extend 4.0. I tried the case with OF2.3 the results are acceptable.

Regards,

[nithinadidela]

I am working on a case which is based on this case.

Can you please let me know if you have succeeded in simulating flow over a cylinder with pimplefoam for Re = 100?


With regards,
Nithin.

Originally Posted by Maimouna

Dear Alexy,

the running is done.
I have two questions please
1. in cotrolDict file (attached)
startTime 0;
endTime 25.0;
deltaT 0.01;

but the running is completed after 1.4, why?

 /*--------------------------------*- 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     pimpleFoam;

startFrom       latestTime;

startTime       0;

stopAt          endTime;

endTime         25.0;

deltaT          0.01; //1e-04

writeControl    adjustableRunTime;

writeInterval   0.1; //5.0e-1

purgeWrite      0;

writeFormat     binary;

writePrecision  6;

writeCompression uncompressed;

timeFormat      scientific;

timePrecision   6;

runTimeModifiable yes;

adjustTimeStep    yes;

maxCo             0.5;

maxDeltaT         2.0e-3;

functions
{
    probes
    {
        type            probes;
        functionObjectLibs ("libsampling.so");
        enabled         true;
        outputControl   timeStep;
        outputInterval  1;
        probeLocations
        (
            ( 0.05   0.0   0.002 )
            ( 0.05   0.01  0.002 )
            ( 0.05   0.01  0.002 )
            ( 0.05   0.01  0.002 )
            ( 0.05   0.01  0.002 )
            ( 0.05   0.01  0.002 )
            ( 0.05   0.01  0.002 )
        );

        fields
        (
            p
        );
    }

    forces
    {
        type        forceCoeffs;
        functionObjectLibs ( "libforces.so" );
        outputControl timeStep;
        outputInterval 1;
        patches
        (
            walls
        );
            directForceDensity no;

        pName       p;
        UName       U;
        rhoName     rhoInf;
        //log         true;
        rhoInf      994.5;
        CofR        ( 0 0 0 );
        liftDir     ( 0 1 0 );
        dragDir     ( 1 0 0 );
        pitchAxis   ( 0 0 1 );
        magUInf     1.787e-4; //1; //0.54
        lRef        0.04;
        Aref        0.0157;
        Aref1        0.004;
        rhoRef      994.5;
    }

    fieldAverage1
    {
        type            fieldAverage;
        functionObjectLibs ("libfieldFunctionObjects.so");
        enabled         true;
        outputControl   outputTime;
        fields
        (
            U
            {
                mean        on;
                prime2Mean  on;
                base        time;
            }

            p
            {
                mean        on;
                prime2Mean  on;
                base        time;
            }
        );
    }
}


// ************************************************************************* //

2. the drag chart is given as attached. Why? I know the drag coefficient figure is tottaly different, whats the wrong?

Best regards

[cryabroad]

Hi kkpal,

I came across this thread and it seems to be very interesting! In my research I use rhoPimpleFoam, I would say that relaxation is definitely needed. The whole idea of using relaxation is to gradually relax the nonlinear nature of the equations and helps to achieve convergence.

I looked through your PIMPLE settings, and I think the problem may be as following. You have only 1 nOuterCorrectors, and you are using relaxation. This means that you are moving the solution from the previous time step to the new time step by let's say only 70% (if the under relaxation factors are 0.7). Obviously you won't get right results unless all the under relaxation factors are set to 1. I normally use much more nOuterCorrectors (20 or so).

I think one thing you could do is to check the conservation of the flow rates, if you are relaxing and using only 1 nOuterCorrector, I expect that the mass is not conserved. In other words, flow information is gradually lost because of the relaxation.