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-   -   Grading leads to simpleFoam crash (http://www.cfd-online.com/Forums/openfoam-meshing-blockmesh/130661-grading-leads-simplefoam-crash.html)

yanyanh March 2, 2014 06:28

Grading leads to simpleFoam crash
 
Hi guys,

I'm currently doing some research on wall functions with a empty 2D domain.
The Mesh is generated by blockmesh and the simpleFoam solver ist used. Everything is working well in parallel and serial, but if I turn on the Grading in the z-direction (perpendicular to the ground) the Solver crashes producing this Error message:

Time = 1

smoothSolver: Solving for Ux, Initial residual = nan, Final residual = nan, No Iterations 1000
smoothSolver: Solving for Uz, Initial residual = nan, Final residual = nan, No Iterations 1000
GAMG: Solving for p, Initial residual = nan, Final residual = nan, No Iterations 1000
time step continuity errors : sum local = nan, global = nan, cumulative = nan
smoothSolver: Solving for epsilon, Initial residual = nan, Final residual = nan, No Iterations 1000
smoothSolver: Solving for k, Initial residual = nan, Final residual = nan, No Iterations 1000
ExecutionTime = 0.53 s ClockTime = 1 s



--> FOAM FATAL IO ERROR:
wrong token type - expected Scalar, found on line 0 the word 'nan'

file: /local/huangya/OpenFOAM/huangya-2.2.0/run/foam/2d_mesh_para_empty_grading/system/data.solverPerformance.U at line 0.

From function operator>>(Istream&, Scalar&)
in file lnInclude/Scalar.C at line 91.

FOAM exiting


This happens only for the grading in z-direction and not for the x-direction. Are there any limitations that I missed using simpleFoam with graded meshs?

Thanks for your time!

Lieven March 2, 2014 07:43

Dear Yanyan,

Welcome to the forum! For us to help us, you should provide a little bit more information.
Could you give us the output of 'checkMesh'? Which are the boundary conditions that you impose? What are the discretization schemes (fvSchemes)?

Cheers,

Lieven

yanyanh March 2, 2014 07:54

Hi Lieven,

Here is the output of CheckMesh:

Code:

Mesh stats
    points:          3402
    internal points:  0
    faces:            6500
    internal faces:  3100
    cells:            1600
    faces per cell:  6
    boundary patches: 5
    point zones:      0
    face zones:      0
    cell zones:      0

Overall number of cells of each type:
    hexahedra:    1600
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    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                 
    outlet              20      42      ok (non-closed singly connected) 
    sides              3200    3402    ok (non-closed singly connected) 
    inlet              20      42      ok (non-closed singly connected) 
    ground              80      162      ok (non-closed singly connected) 
    top                80      162      ok (non-closed singly connected) 

Checking geometry...
    Overall domain bounding box (0 0 0) (5000 1 500)
    Mesh (non-empty, non-wedge) directions (1 0 1)
    Mesh (non-empty) directions (1 0 1)
    All edges aligned with or perpendicular to non-empty directions.
    Boundary openness (-5.67186378575e-21 -6.11290791373e-16 0) OK.
    Max cell openness = 1.35710844948e-16 OK.
    Max aspect ratio = 9.98190321022 OK.
    Minimum face area = 6.26133099908. Maximum face area = 3913.33187443.  Face area magnitudes OK.
    Min volume = 391.333187443. Max volume = 3913.33187443.  Total volume = 2500000.  Cell volumes OK.
    Mesh non-orthogonality Max: 0 average: 0
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 3.63068469086e-13 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

End

and fvSchemes:

Code:

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

ddtSchemes
{
    default            steadyState;
}

gradSchemes
{
    default            Gauss linear;
}

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

laplacianSchemes
{
    default            Gauss linear limited corrected 0.333;
}

interpolationSchemes
{
    default            linear;
}

snGradSchemes
{
    default            limited corrected 0.333;
}

fluxRequired
{
    default            no;
    p;
}


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

It's quite standard. I took the turbineSiting tutorial file and modified it. So I deleted the two disks and used empty type boundary for the sides.

Thanks!

yanyanh March 2, 2014 12:08

I solved the problem. There was a mistake with the BC at the Inlet.


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