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MRFSimpleFoam diverges (Pre-Processing errors?)

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Old   December 11, 2015, 14:24
Default MRFSimpleFoam diverges (Pre-Processing errors?)
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Julian
Join Date: Dec 2015
Location: Berlin
Posts: 6
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Hello community,

I have a problem with my MRFSimpleFoam case.

At first a bit about my problem:
For a class in university I have to simulate a stirred tank with a rushton turbine. We did the lid driven cavity case as an example and now we have to solve the tank ourselves.

I created my mesh in pointwise and exported it to OpenFoam. CheckMesh says that everything is okay, except a few non-orthogonal faces.

Code:
Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
    points:           487989
    faces:            3384189
    internal faces:   3303318
    cells:            1504134
    faces per cell:   4.44608
    boundary patches: 6
    point zones:      0
    face zones:       1
    cell zones:       1

Overall number of cells of each type:
    hexahedra:     0
    prisms:        631533
    wedges:        0
    pyramids:      39438
    tet wedges:    0
    tetrahedra:    833163
    polyhedra:     0

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
    Patch               Faces    Points   Surface topology                  
    Baffles             13722    6942     ok (non-closed singly connected)  
    Tank                11598    5848     ok (non-closed singly connected)  
    Top                 7351     4883     ok (non-closed singly connected)  
    impeller            40568    20301    ok (non-closed singly connected)  
    shaft-rt            845      455      ok (non-closed singly connected)  
    shaft-st            6787     3426     ok (non-closed singly connected)  

Checking geometry...
    Overall domain bounding box (-0.15 -0.15 0) (0.15 0.15 0.3)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Boundary openness (1.34546e-18 -3.36675e-18 -5.92271e-17) OK.
    Max cell openness = 5.1542e-15 OK.
    Max aspect ratio = 376.953 OK.
    Minimum face area = 7.1479e-12. Maximum face area = 0.000129353.  Face area magnitudes OK.
    Min volume = 5.17032e-16. Max volume = 4.46924e-07.  Total volume = 0.0211778.  Cell volumes OK.
    Mesh non-orthogonality Max: 89.9581 average: 23.0521
   *Number of severely non-orthogonal (> 70 degrees) faces: 43679.
    Non-orthogonality check OK.
  <<Writing 43679 non-orthogonal faces to set nonOrthoFaces
    Face pyramids OK.
    Max skewness = 2.46475 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

End
I tried to resolve my problem with the non-orthogonal faces, but so far nothing on that end.

Since I only did the cavity case, I tried to assemble the fvsolution, fvscheme and fvoptions files myself. I played a little bit with the algorithms and tried euler instead of steadyState, too.
Code:
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    p
    {
        solver          PCG;
        preconditioner
        {
            preconditioner  GAMG;
            smoother        DICGaussSeidel;
            nPreSweeps      0;
            nPostSweeps     2;
            nBottomSweeps   2;
            cacheAgglomeration true;
            nCellsInCoarsestLevel 1000;
            agglomerator    faceAreaPair;
            mergeLevels     1;
        }
        tolerance       1e-5;
        relTol          0.01;
    }

    "(U|k|epsilon)"
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-05;
        relTol          0.0;
    }

    Phi
    {
        solver GAMG;
        smoother DIC;
        cacheAgglomeration on;
        agglomerator faceAreaPair;
        nCellsInCoarsestLevel 10;
        mergeLevels 1;

        tolerance 1e-06;
        relTol 0.01;
    }
}
SIMPLE
{
        nNonOrthogonalCorrectors 3;

        pRefCell  0;
        pRefValue 0;

    

    residualControl
    {
        p               1e-4;
        U               1e-4;
        "(k|epsilon)"   1e-4;
    }

}

potentialFlow
{
    nNonOrthogonalCorrectors 10;
     PhiRefCell 1;
     PhiRefValue 0;
}

relaxationFactors
{
    fields
    {
        p               0.3;
    }
    equations
    {
        U               0.5;
        k               0.5;
        epsilon         0.5;
    }
}
Code:
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default         steadyState;
}

gradSchemes
{
    default         Gauss linear;
    grad(p)         cellMDLimited Gauss linear 0.5;
    grad(U)         cellMDLimited Gauss linear 0.5;
}

divSchemes
{
    default                      none;
//    div(phi,U)                   bounded Gauss upwind;
    div(phi,U)                   bounded Gauss linearUpwind grad(U);
     div(phi,k)                  bounded Gauss upwind;
    div(phi,epsilon)             bounded Gauss upwind;
    div((nuEff*dev(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
    default         Gauss linear limited 1.0;
    laplacian((1|A(U)),p) Gauss linear limited 0.5;
    laplacian(nuEff,U) Gauss linear limited 0.5;
    laplacian(DkEff,k) Gauss linear limited 0.333;
    laplacian(DepsilonEff,epsilon) Gauss linear limited 0.3333;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         corrected;
}

fluxRequired
{
    default         no;
    p               ;
    Phi             ;
}
Code:
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvOptions;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

MRF1
{
    type            MRFSource;
    active          true;
    selectionMode   cellZone;
    cellZone        rotor-cells;

    MRFSourceCoeffs
    {
        active      true;
        origin      (0 0 0);
        axis        (0 0 1);
        omega       -10,472;
    }
}
Maybe I did something wrong in that area.

Here is the result file from SimpleFoam:
Code:
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 RAS turbulence model kEpsilon
kEpsilonCoeffs
{
    Cmu             0.09;
    C1              1.44;
    C2              1.92;
    sigmaEps        1.3;
}

Creating finite volume options from "system/fvOptions"

Selecting finite volume options model type MRFSource
    Source: MRF1
    - applying source for all time
    - selecting cells using cellZone rotor-cells
    - selected 670952 cell(s) with volume 0.000425687


SIMPLE: convergence criteria
    field p     tolerance 0.0001
    field U     tolerance 0.0001
    field "(k|epsilon)"     tolerance 0.0001


Starting time loop

Time = 0.005

DILUPBiCG:  Solving for Ux, Initial residual = 1, Final residual = 3.12329e-07, No Iterations 4
DILUPBiCG:  Solving for Uy, Initial residual = 1, Final residual = 3.19712e-07, No Iterations 4
DILUPBiCG:  Solving for Uz, Initial residual = 1, Final residual = 1.30184e-06, No Iterations 4
GAMGPCG:  Solving for p, Initial residual = 1, Final residual = 0.00466828, No Iterations 3
GAMGPCG:  Solving for p, Initial residual = 0.809306, Final residual = 0.00262468, No Iterations 2
GAMGPCG:  Solving for p, Initial residual = 0.116645, Final residual = 0.000305393, No Iterations 2
GAMGPCG:  Solving for p, Initial residual = 0.0346045, Final residual = 8.29727e-05, No Iterations 2
time step continuity errors : sum local = 9.32531e-07, global = 8.45741e-21, cumulative = 8.45741e-21
DILUPBiCG:  Solving for epsilon, Initial residual = 0.117342, Final residual = 7.0707e-07, No Iterations 3
DILUPBiCG:  Solving for k, Initial residual = 1, Final residual = 1.18168e-07, No Iterations 5
ExecutionTime = 21.17 s  ClockTime = 27 s

Time = 0.01

DILUPBiCG:  Solving for Ux, Initial residual = 0.913458, Final residual = 6.58616e-07, No Iterations 4
DILUPBiCG:  Solving for Uy, Initial residual = 0.913014, Final residual = 7.41462e-07, No Iterations 4
DILUPBiCG:  Solving for Uz, Initial residual = 0.913583, Final residual = 6.82136e-07, No Iterations 4
GAMGPCG:  Solving for p, Initial residual = 0.235286, Final residual = 0.00084983, No Iterations 3
GAMGPCG:  Solving for p, Initial residual = 0.615328, Final residual = 0.00340317, No Iterations 3
GAMGPCG:  Solving for p, Initial residual = 0.971477, Final residual = 0.00906469, No Iterations 2
GAMGPCG:  Solving for p, Initial residual = 0.995672, Final residual = 0.00617046, No Iterations 2
time step continuity errors : sum local = 0.0281242, global = -5.23062e-17, cumulative = -5.22977e-17
DILUPBiCG:  Solving for epsilon, Initial residual = 1, Final residual = 1.07123e-06, No Iterations 5
bounding epsilon, min: -28.7564 max: 2.04466e+15 average: 3.77328e+09
DILUPBiCG:  Solving for k, Initial residual = 1, Final residual = 1.2268e-07, No Iterations 3
ExecutionTime = 36.44 s  ClockTime = 43 s

Time = 0.015

DILUPBiCG:  Solving for Ux, Initial residual = 0.561159, Final residual = 6.8168e-06, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.561325, Final residual = 6.80877e-06, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.561162, Final residual = 6.81625e-06, No Iterations 2
GAMGPCG:  Solving for p, Initial residual = 0.999947, Final residual = 0.00903246, No Iterations 5
GAMGPCG:  Solving for p, Initial residual = 1.74608e-05, Final residual = 7.51276e-07, No Iterations 1
GAMGPCG:  Solving for p, Initial residual = 0.000884558, Final residual = 3.59299e-06, No Iterations 2
GAMGPCG:  Solving for p, Initial residual = 0.00412373, Final residual = 1.64771e-05, No Iterations 2
time step continuity errors : sum local = 3.93065e+13, global = -0.0175471, cumulative = -0.0175471
DILUPBiCG:  Solving for epsilon, Initial residual = 1, Final residual = 1.94567e-06, No Iterations 5
DILUPBiCG:  Solving for k, Initial residual = 1, Final residual = 1.04978e-07, No Iterations 2
ExecutionTime = 50.71 s  ClockTime = 58 s

Time = 0.02

DILUPBiCG:  Solving for Ux, Initial residual = 0.0561779, Final residual = 4.60607e-07, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.325571, Final residual = 2.86478e-06, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.0501521, Final residual = 4.86382e-09, No Iterations 2
GAMGPCG:  Solving for p, Initial residual = 1, Final residual = 494.301, No Iterations 1001
GAMGPCG:  Solving for p, Initial residual = 1, Final residual = 1.40105e-14, No Iterations 1
GAMGPCG:  Solving for p, Initial residual = 0.9441, Final residual = 1.72134e-15, No Iterations 1
GAMGPCG:  Solving for p, Initial residual = 0.0874721, Final residual = 7.70611e-16, No Iterations 1
time step continuity errors : sum local = 9.57218e+39, global = -1.65747e+25, cumulative = -1.65747e+25
DILUPBiCG:  Solving for epsilon, Initial residual = 1, Final residual = 8.76851e-06, No Iterations 16
DILUPBiCG:  Solving for k, Initial residual = 9.07054e-22, Final residual = 9.07054e-22, No Iterations 0
ExecutionTime = 854.54 s  ClockTime = 931 s

Time = 0.025

DILUPBiCG:  Solving for Ux, Initial residual = 0.545841, Final residual = 8.00364e-06, No Iterations 44
DILUPBiCG:  Solving for Uy, Initial residual = 0.545779, Final residual = 4.74215e-06, No Iterations 44
DILUPBiCG:  Solving for Uz, Initial residual = 0.54569, Final residual = 3.80886e-06, No Iterations 43
Thank you very much for your help!
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