[shaiashe]

Hi,

I need help with my exploding simulation.
my mesh is quite large, but I made sure it's of high quality (non-ortho <70) and skewness < 3.5.

    Overall domain bounding box (-150 -200 -82) (769 0 82)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (5.3231506e-17 -1.9192017e-15 -7.1636234e-16) OK.
    Max cell openness = 8.413231e-16 OK.
    Max aspect ratio = 24.810447 OK.
    Minimum face area = 6.1169547e-06. Maximum face area = 18.649767.  Face area magnitudes OK.
    Min volume = 1.6255701e-06. Max volume = 87.633202.  Total volume = 30060593.  Cell volumes OK.
    Mesh non-orthogonality Max: 64.998208 average: 2.1675072
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 3.2694797 OK.
    Coupled point location match (average 0) OK.
    Face tets OK.
   *Edges too small, min/max edge length = 4.824642e-09 4.4238302, number too small: 12
  <<Writing 12 points on short edges to set shortEdges
   *There are 441 faces with concave angles between consecutive edges. Max concave angle = 66.960231 degrees.
  <<Writing 441 faces with concave angles to set concaveFaces
    Face flatness (1 = flat, 0 = butterfly) : min = 0.68602191  average = 0.9999684
   *There are 6 faces with ratio between projected and actual area < 0.8
    Minimum ratio (minimum flatness, maximum warpage) = 0.68602191
  <<Writing 6 warped faces to set warpedFaces
    Cell determinant (wellposedness) : minimum: 0 average: 1.0646607
 ***Cells with small determinant (< 0.001) found, number of cells: 548
  <<Writing 548 under-determined cells to set underdeterminedCells
 ***Concave cells (using face planes) found, number of cells: 21473
  <<Writing 21473 concave cells to set concaveCells
    Face interpolation weight : minimum: 0.024440083 average: 0.49344369
 ***Faces with small interpolation weight (< 0.05) found, number of faces: 210
  <<Writing 210 faces with low interpolation weights to set lowWeightFaces
    Face volume ratio : minimum: 0.0132952 average: 0.97292238
    Face volume ratio check OK.

Even when I close off all of the boundaries as walls, the simulation explodes on the 2nd step with huge courant numbers (both of them).
with

Phase-1 volume fraction = 0.49988109  Min(alpha.water) = -1.2127875e-64  Max(alpha.water) = 1.0000392

does that mean the water is evaporating?

I set my fvSolution as :

FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    "alpha.water.*"
    {
        nAlphaCorr      2;
        nAlphaSubCycles 1;
        cAlpha          1;
        icAlpha         0;

        MULESCorr       yes;
        nLimiterIter    10;
        alphaApplyPrevCorr  yes;

        solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-8;
        relTol          0;
        minIter         1;
    }

    "pcorr.*"
    {

        solver          GAMG;//PCG
        preconditioner  DIC;
        smoother        GaussSeidel;//Add by pol
        tolerance       1e-10; //1e-10
        relTol          0;
    }

    p_rgh
    {
        solver          GAMG;
        tolerance       1e-4;  //1e-7
        relTol          0.01;
        smoother        GaussSeidel;  //DIC
        nPreSweeps      0;
        nPostSweeps     2;
        cacheAgglomeration true; //false
        nCellsInCoarsestLevel 2090;//1000
        agglomerator    faceAreaPair;
        mergeLevels     1;

    }

    p_rghFinal
    {
        solver          GAMG;
        tolerance       1e-6;  //1e-7
        relTol          0.0;
        smoother        GaussSeidel;  //DIC
        nPreSweeps      0;
        nPostSweeps     2;
        cacheAgglomeration true; //false
        nCellsInCoarsestLevel 2090;//1000
        agglomerator    faceAreaPair;
        mergeLevels     1;
        /*$p_rgh;
        tolerance       1e-09;//1e-09
        relTol          0;*/
    }

    "(U|k|omega).*"
    {
        solver          smoothSolver;
        smoother        symGaussSeidel;
        nSweeps         1;
        tolerance       1e-7;
        relTol          0.1;
        minIter         1;
    };
    cellDisplacement
    {
        solver          GAMG;
        smoother        GaussSeidel;
        tolerance       1e-7;
        relTol          0.01;
    }	
}

PIMPLE
{
    momentumPredictor   no;

    nOuterCorrectors    5;
    nCorrectors         5;
    nNonOrthogonalCorrectors 2;
	correctPhi          yes;
    maxCo               1;
    maxAlphaCo          1;

    rDeltaTSmoothingCoeff 0.05;
    rDeltaTDampingCoeff 0.5;
    nAlphaSpreadIter    0;
    nAlphaSweepIter     0;
    maxDeltaT           1;
    residualControl
    {
        U
        {
                tolerance  1e-03;
                relTol     0;
        }

        p_rgh
        {
                tolerance  1e-03;
                relTol     0;
        }

    }	
}

relaxationFactors
{
    equations
    {
		p 0.3;
		U 0.7;
		k 0.7;
		omega 0.7;
    }
}

cache
{
    grad(U);
}

any advise?
Cheers,

[shaiashe]

it looks like the flow is escaping through the top boundary; and that the explosion is related to the air fraction