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Pressure iterations reach max

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Old   September 5, 2021, 07:31
Post Pressure iterations reach max
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Said CATALBAS
Join Date: Feb 2020
Location: Türkiye
Posts: 46
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Hi,

I'm solving a natural convection case with the buoyantPimpleFoam. The pressure solver reaches maximum iteration nearly all outer loops even if the checkMesh results looks fine and also the convergence criteria not tight.
  • GAMG: Solving for p_rgh, Initial residual = 0.0475859098409, Final residual = 0.0157404857286, No Iterations 300
I've tried to get better mesh, more robust schemes (upwind), reduce relaxation factors and tolerances but none of them worked. Maybe I have missed something about boundary condition but they look fine either to me. Why do not converge? I am open to any suggestions. Files are attached.

Kind regards,
Said.

For quick look;


Code:
cells:            984891
Checking geometry...
     Overall domain bounding box (-0.00334 -0.00334 -1.90819582357e-17) (0.00334 0.00334 0.08684)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (2.79406534204e-16 6.89998282164e-16 1.24139673575e-16) OK.
    Max cell openness = 2.51976925248e-16 OK.
    Max aspect ratio = 6.09829454585 OK.
    Minimum face area = 6.12453563709e-09. Maximum face area = 1.55316884489e-07.  Face area magnitudes OK.
    Min volume = 2.2134204e-13. Max volume = 1.88150115538e-11.  Total volume = 2.30561433658e-06.  Cell volumes OK.
    Mesh non-orthogonality Max: 64.9766553786 average: 15.615597926
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.837135365112 OK.
     Coupled point location match (average 0) OK.
Code:
    p_rgh
     {
    solver           GAMG;
    tolerance        1e-4;
    relTol           0.05;
    smoother         GaussSeidel;
    nPreSweeps     0;
    nPostSweeps     2;
    nFinestSweeps    2;
    scaleCorrection  yes;
    directSolveCoarsestLevel false;
    cacheAgglomeration    on;
    nCellsInCoarsestLevel 1000;
    agglomerator     faceAreaPair;
    minIter           4;
    maxIter           300;
    mergeLevels      1;
    }

    p_rghFinal
    {
    solver           GAMG;
    tolerance        1e-6;
    relTol           0.05;
    smoother         GaussSeidel;
    nPreSweeps     0;
    nPostSweeps     2;
    nFinestSweeps    2;
    scaleCorrection  yes;
    directSolveCoarsestLevel false;
    cacheAgglomeration    on;
    nCellsInCoarsestLevel 1000;
    agglomerator     faceAreaPair;
    minIter           4;
    maxIter           300;
    mergeLevels      1;
     }
Code:
ddtSchemes
{
    default         Euler;
}
gradSchemes
{
    //default     cellMDLimited Gauss linear 0.5;
    //grad(U)    cellMDLimited Gauss linear 0.5;
    default     cellLimited Gauss linear 0.5;
    grad(U)    cellLimited Gauss linear 0.5;
}
divSchemes
{
    default         none;
    //div(phi,U)      Gauss linearUpwind grad(U);
    //div(phi,K)      Gauss linearUpwind default;
    //div(phi,h)      Gauss linearUpwind default;
    div(phi,U)      Gauss upwind grad(U);
    div(phi,K)      Gauss upwind default;
    div(phi,h)      Gauss upwind default;
    div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}
laplacianSchemes
{
    default         Gauss linear limited 0.777;
}
interpolationSchemes
{
    default         linear;
}
snGradSchemes
{
    default         limited 0.777;
}
Attached Files
File Type: zip nat_Conv_BCC.zip (24.8 KB, 1 views)

Last edited by saidc.; September 12, 2021 at 10:36.
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