[fafnir]

Hello everyone,

I am running a 2D oscillating airfoil simulation with rhoPimpleFOAM in OpenFOAM v2012 which runs very slow.

The mesh was designed to have 85,000 cells in the rotating zone, and 40,000 cells in the background stationary zone, with y+ value of 1. The cellzone was divided by the following command;
splitMeshRegions -makeCellZones -overwrite

The boundary condition was made as follows

PHP Code:

7
(
    cyclic1
    {
        type            cyclicAMI;
        inGroups        1(cyclicAMI);
        nFaces          300;
        startFace       188845;
        matchTolerance  0.0001;
        transform       unknown;
        neighbourPatch  cyclic2;
        AMIMethod       faceAreaWeightAMI;
        restartUncoveredSourceFace 1;
    }
    cyclic2
    {
        type            cyclicAMI;
        inGroups        1(cyclicAMI);
        nFaces          250;
        startFace       189145;
        matchTolerance  0.0001;
        transform       unknown;
        neighbourPatch  cyclic1;
        AMIMethod       faceAreaWeightAMI;
        restartUncoveredSourceFace 1;
    }
    inlet
    {
        type            patch;
        nFaces          200;
        startFace       189395;
    }
    left
    {
        type            empty;
        inGroups        1(empty);
        nFaces          123130;
        startFace       189595;
    }
    outlet
    {
        type            patch;
        nFaces          200;
        startFace       312725;
    }
    right
    {
        type            empty;
        inGroups        1(empty);
        nFaces          123130;
        startFace       312925;
    }
    wall
    {
        type            wall;
        inGroups        1(wall);
        nFaces          586;
        startFace       436055;
    }
) 


and the fvSolution:

PHP Code:

solvers
{
    p
    {
        solver                GAMG;
        tolerance            1e-7;
        relTol                0;
        smoother            GaussSeidel;
        minIter                1;
        maxIter                100;
        nPreSweeps        0;
        nPostSweeps        2;
        nFinestSweeps    2;
        cacheAgglomeration    true;
        agglomerator                faceAreaPair;
        nCellsInCoarestLevel    100;
        mergeLevels                        1;
    }

    pFinal
    {
        $p;
        tolerance       1e-7;
        relTol          0;
    }

    "(pcorr|pcorrD1)"
    {
        solver           GAMG;
        tolerance        1e-3;
        relTol           0;
        smoother         GaussSeidel;
        minIter                1;
        maxIter                10;
        nPreSweeps        0;
        nPostSweeps        2;
        nFinestSweeps    2;
        cacheAgglomeration    true;
        agglomerator                faceAreaPair;
        nCellsInCoarestLevel    10;
        mergeLevels                        1;
    }
    
    "(pcorr|pcorrD1)Final"
    {
        solver           GAMG;
        tolerance        1e-3;
        relTol           0;
        smoother         GaussSeidel;
    }

    "(rho|U|h|k|epsilon|omega|nuTilda|e)"
    {
        solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-06;
        relTol          0.01;
    }

    "(rho|U|h|k|epsilon|omega|nuTilda|e)Final"
    {
        $U;
        tolerance       1e-7;
        relTol          0;
    }

}

PIMPLE
{
        correctPhi      yes;
    momentumPredictor yes;
    transonic       no;
    nOuterCorrectors 1;
    nCorrectors     3;
    nNonOrthogonalCorrectors 2;
    rhoMin          rhoMin [ 1 -3 0 0 0 ] 0.1;
    rhoMax          rhoMax [ 1 -3 0 0 0 ] 3.0;
    startAveraging    0.15;

    residualControl
    {
        "(U|k|epsilon|omega|Ud|rhod|Ud2|rhod2)"
        {
            relTol          0;
            tolerance       0.0001;
        }
    }

    turbOnFinalIterOnly off;
}

relaxationFactors
{
    fields
    {
        "p"                0.3;
        "rho"            0.3;
        "k"                0.7;
        "omega"            0.7;
        "Ud"            0.7;
        "rhod"            0.7;
    }
    equations
    {
        "(U|pp|h|k|epsilon|omega|Ud|rhod)"            0.5;
        "(U|pp|h|k|epsilon|omega|Ud|rhod)Final"        1.0;
    }
} 


For 1 iteration with 24 processors, it takes 0.9~1s for the AMI mesh update and 0.03-0.04s for the rhoPimpleFoam calculation. Is this a reasonable execution time for the AMI mesh update? Are there any tips to speed up the calculation?

Any tips to improve the performance would be greatly appreciated.