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-   -   Is steady state solver grid dependent? (http://www.cfd-online.com/Forums/openfoam/114991-steady-state-solver-grid-dependent.html)

mmkr825 March 21, 2013 08:43

Is steady state solver grid dependent?
 
Hi Foamers,
I am doing simulations on 2D rectangular channel by using steady state solver. I prepared my solver by modifying "simpleFoam" solver. The dimensions (length*breadth) of the channel are 0.143*0.0017 (m). My geometry has 500*10 grids in x- and y- directions respectively. When i run my solver with 500*10 grids, it is giving good results. But when I refine grids (say 600*15) or increase the dimensions of the channel, after running few iterations it is giving the following error.

Error:
Code:

#0  Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1  Foam::sigFpe::sigHandler(int) in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2  Uninterpreted:
#3  in "/lib/i386-linux-gnu/libm.so.6"
#4  pow in "/lib/i386-linux-gnu/libm.so.6"
#5  Foam::pow(Foam::Field<double>&, Foam::UList<double> const&, double const&) in "/opt/openfoam211/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#6  Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::pow<Foam::fvPatchField, Foam::volMesh>(Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > const&, Foam::dimensioned<double> const&) at /opt/openfoam211/src/OpenFOAM/lnInclude/GeometricScalarField.C:273
#7 
 at /opt/openfoam211/src/OpenFOAM/lnInclude/GeometricScalarField.C:349
#8  __libc_start_main in "/lib/i386-linux-gnu/libc.so.6"
#9 
 in "/home/malli_reddy/OpenFOAM/malli_reddy-2.1.1/platforms/linuxGccDPOpt/bin/SBM25Foam"
Floating point exception

The geometry pass the checkMesh test. Could someone please help me to understand the reason for the error. Thanks in advance.

Regards
Reddy

fumiya March 22, 2013 10:33

Could you upload your case?

Best regards,
Fumiya

mmkr825 March 22, 2013 10:44

Hi Fumiya,
Thanks for reply. My case is simple 2D channel.
My blockMeshDict:
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;
    object      blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.001;

vertices
(
    (0 0 0)
    (173 0 0)
    (173 1.7 0)
    (0 1.7 0)
    (0 0 0.1)
    (173 0 0.1)
    (173 1.7 0.1)
    (0 1.7 0.1)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (1000 10 1) simpleGrading (1 1 1)
);

edges
(
);

boundary
(
    leftWall
    {
        type patch;
        faces
        (
            (0 4 7 3)
        );
    }
    fixedWalls
    {
        type wall;
        faces
        (
            (7 6 2 3)
            (1 5 4 0)
        );
    }
    rightWall
    {
    type patch;
    faces
    (
        (2 6 5 1)
    );
    }
    frontAndBack
    {
        type empty;
        faces
        (
            (0 3 2 1)
            (4 5 6 7)
        );
    }
);

mergePatchPairs
(
);

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

Regards
Mallikarjuna

fumiya March 22, 2013 12:56

Hi Mallikarjuna,

Your mesh seems to be OK.
Could you share the files in 0 and system directories?

Best regards,
Fumiya

mmkr825 March 22, 2013 14:46

Hi Fumiya,
Very much thanks for your kindness. My solver is highly non-linear. In my solver i encounter shear rate(magnitude of strain tensor). So my solver needs good initial guess for velocity. So i am attaching my solver and case file with initial guess for velocity.

Solver:
https://www.dropbox.com/s/tm8i4y2u0a...M25Foam.tar.gz

Case File:
https://www.dropbox.com/s/bz7u10bc16urpdc/case.tar.gz

I am very thankful to you if you guide me in correct path. Thanks in advance.

Regards
Mallikarjuna.


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