Negative alpha1 using interDyMFoam

jrrygg · February 21, 2013, 10:06

Hi,

I am currently trying to do a simulation with a high speed water jet acting on rotating Pelton buckets.

Unfortunately, the simulation crashes before giving me any results. The alpha1 minimum volume fractions are negative, and I wonder if this is what is making the simulation crash? I am not sure about the setup of fvSolution and fvSchemes, so my guess is that these cause the negative alphas.

The log output of some early timesteps:

Code:

Interface Courant Number mean: 1.624315938e-07 max: 0.1091097517
Courant Number mean: 0.000375590931 max: 0.1091097517
deltaT = 3.491717999e-07
Time = 1.533552435e-06

solidBodyMotionFunctions::rotatingMotion::transformation(): Time = 1.533552435e-06 transformation: ((0 0 0) (0.9999999987 (0 5.078761069e-05 0)))
AMI: Creating addressing and weights between 14964 source faces and 14964 target faces
AMI: Patch source weights min/max/average = 0.9950716382, 1.394205984, 1.000575435
AMI: Patch target weights min/max/average = 0.9950442673, 1.365096275, 1.000564816
Execution time for mesh.update() = 1.58 s
MULES: Solving for alpha1
Phase-1 volume fraction = 5.44966545e-07  Min(alpha1) = -1.791466825e-20  Max(alpha1) = 1
MULES: Solving for alpha1
Phase-1 volume fraction = 5.823644789e-07  Min(alpha1) = -1.038904174e-20  Max(alpha1) = 1
MULES: Solving for alpha1
Phase-1 volume fraction = 6.197624128e-07  Min(alpha1) = -7.825973141e-20  Max(alpha1) = 1
MULES: Solving for alpha1
Phase-1 volume fraction = 6.571603467e-07  Min(alpha1) = -4.473487596e-20  Max(alpha1) = 1
GAMG:  Solving for p_rgh, Initial residual = 0.01655311958, Final residual = 6.810976661e-09, No Iterations 15
time step continuity errors : sum local = 1.769268728e-15, global = 1.368834199e-17, cumulative = -4.282017598e-08
GAMG:  Solving for p_rgh, Initial residual = 0.003952141467, Final residual = 6.617702388e-09, No Iterations 11
time step continuity errors : sum local = 1.400029147e-15, global = -1.456483218e-16, cumulative = -4.282017612e-08
GAMG:  Solving for p_rgh, Initial residual = 0.001011700049, Final residual = 3.845282687e-09, No Iterations 10
time step continuity errors : sum local = 8.217598588e-16, global = -5.254782802e-17, cumulative = -4.282017618e-08
GAMG:  Solving for p_rgh, Initial residual = 0.000554491584, Final residual = 6.972409284e-09, No Iterations 9
time step continuity errors : sum local = 1.490644691e-15, global = -1.291619314e-16, cumulative = -4.282017631e-08
GAMG:  Solving for p_rgh, Initial residual = 0.0003465827588, Final residual = 5.393514794e-09, No Iterations 9
time step continuity errors : sum local = 1.153062298e-15, global = 1.070930183e-16, cumulative = -4.28201762e-08
GAMGPCG:  Solving for p_rgh, Initial residual = 0.0002396514594, Final residual = 2.174711367e-10, No Iterations 5
time step continuity errors : sum local = 4.64927874e-17, global = -3.972436362e-19, cumulative = -4.28201762e-08
ExecutionTime = 223.19 s  ClockTime = 233 s

Interface Courant Number mean: 1.916717685e-07 max: 0.1287661148
Courant Number mean: 0.0004432945119 max: 0.1287661148
deltaT = 4.019038676e-07
Time = 1.935456303e-06

solidBodyMotionFunctions::rotatingMotion::transformation(): Time = 1.935456303e-06 transformation: ((0 0 0) (0.9999999979 (0 6.409771126e-05 0)))
AMI: Creating addressing and weights between 14964 source faces and 14964 target faces
AMI: Patch source weights min/max/average = 0.9932927434, 1.400417156, 1.000607698
AMI: Patch target weights min/max/average = 0.9925058446, 1.363865653, 1.000594273
Execution time for mesh.update() = 1.59 s
MULES: Solving for alpha1
Phase-1 volume fraction = 7.002037891e-07  Min(alpha1) = -3.274013142e-20  Max(alpha1) = 1
MULES: Solving for alpha1
Phase-1 volume fraction = 7.432472314e-07  Min(alpha1) = -6.563983597e-20  Max(alpha1) = 1
MULES: Solving for alpha1
Phase-1 volume fraction = 7.862906737e-07  Min(alpha1) = -1.433173356e-20  Max(alpha1) = 1
MULES: Solving for alpha1
Phase-1 volume fraction = 8.293341161e-07  Min(alpha1) = -1.93310652e-20  Max(alpha1) = 1
GAMG:  Solving for p_rgh, Initial residual = 0.01412494318, Final residual = 5.132243665e-09, No Iterations 15
time step continuity errors : sum local = 1.437750713e-15, global = 1.507869969e-17, cumulative = -4.282017618e-08
GAMG:  Solving for p_rgh, Initial residual = 0.003289228668, Final residual = 8.303451587e-09, No Iterations 11
time step continuity errors : sum local = 2.021746186e-15, global = -1.823752452e-16, cumulative = -4.282017637e-08
GAMG:  Solving for p_rgh, Initial residual = 0.0009262395848, Final residual = 9.932632803e-09, No Iterations 9
time step continuity errors : sum local = 2.455684309e-15, global = -3.964969215e-16, cumulative = -4.282017676e-08
GAMG:  Solving for p_rgh, Initial residual = 0.0004916397871, Final residual = 6.729308374e-09, No Iterations 9
time step continuity errors : sum local = 1.664547207e-15, global = -1.628362513e-16, cumulative = -4.282017693e-08
GAMG:  Solving for p_rgh, Initial residual = 0.000302596381, Final residual = 4.941746421e-09, No Iterations 9
time step continuity errors : sum local = 1.222443575e-15, global = 1.240361068e-16, cumulative = -4.28201768e-08
GAMGPCG:  Solving for p_rgh, Initial residual = 0.0002065366047, Final residual = 1.986903846e-10, No Iterations 5
time step continuity errors : sum local = 4.914866401e-17, global = -3.566772216e-19, cumulative = -4.28201768e-08
ExecutionTime = 252.05 s  ClockTime = 263 s

My fvSolution:

Code:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.1.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    pcorr
    {
        solver          PCG;
        preconditioner
        {
            preconditioner  GAMG;
            tolerance       1e-05;
            relTol          0;
            smoother        DICGaussSeidel;
            nPreSweeps      0;
            nPostSweeps     2;
            nFinestSweeps   2;
            cacheAgglomeration false;
            nCellsInCoarsestLevel 10;
            agglomerator    faceAreaPair;
            mergeLevels     1;
        }

        tolerance       1e-05;
        relTol          0;
        maxIter         100;
    }

    p_rgh
    {
        solver          GAMG;
        tolerance       1e-08;
        relTol          0;
        smoother        DIC;
        nPreSweeps      0;
        nPostSweeps     2;
        nFinestSweeps   2;
        cacheAgglomeration true;
        nCellsInCoarsestLevel 10;
        agglomerator    faceAreaPair;
        mergeLevels     1;
    }

    p_rghFinal
    {
        solver          PCG;
        preconditioner
        {
            preconditioner  GAMG;
            tolerance       2e-09;
            relTol          0;
            nVcycles        2;
            smoother        DICGaussSeidel;
            nPreSweeps      2;
            nPostSweeps     2;
            nFinestSweeps   2;
            cacheAgglomeration true;
            nCellsInCoarsestLevel 10;
            agglomerator    faceAreaPair;
            mergeLevels     1;
        }

        tolerance       2e-09;
        relTol          0;
        maxIter         20;
    }

    U
    {
        solver          smoothSolver;
        smoother        GaussSeidel;
        tolerance       1e-06;
        relTol          0;
        nSweeps         1;
    }
}

PIMPLE
{
    momentumPredictor no;
    nCorrectors     6;
    nNonOrthogonalCorrectors 0;
    nAlphaCorr      1;
    nAlphaSubCycles 4;
    cAlpha          1.5;
    correctPhi      no;

}

relaxationFactors
{
    fields
    {
    }
    equations
    {
        "U.*"           1;
    }
}


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

My fvSchemes:

Code:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.1.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default         Euler;
}

gradSchemes
{
    default         Gauss linear;
}

divSchemes
{
    div(rho*phi,U)  Gauss upwind;
    div(phi,alpha)  Gauss vanLeer;
    div(phirb,alpha) Gauss interfaceCompression;
}

laplacianSchemes
{
    default         Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         corrected;
}

fluxRequired
{
    default         no;
    p_rgh;
    pcorr;
    alpha;
}


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

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