[alvariten]

Hi people,

I'm new user in OF and I appreciate any reply. I'm trying to solve a simple case with high pressure at inlet and low pressure at outlet. And the velocity is unknown in both cases (one of the purposes is to determinate the velocity at output).

First I did was check the mesh, and I think this is ok.

Create polyMesh for time = 0

Time = 0

Mesh stats
    points:           352020
    faces:            1020530
    internal faces:   985870
    cells:            334400
    faces per cell:   6
    boundary patches: 4
    point zones:      0
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     334400
    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                  
    fixedwall           11160    11531    ok (non-closed singly connected)  
    inlet               3200     3321     ok (non-closed singly connected)  
    outlet              1600     1671     ok (non-closed singly connected)  
    sym                 18700    19060    ok (non-closed singly connected)  

Checking geometry...
    Overall domain bounding box (-1.5 -5.55112e-17 -0.7) (0 1.5 1.95)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Boundary openness (-1.45026e-14 1.20956e-14 3.91972e-16) OK.
    Max cell openness = 4.0813e-16 OK.
    Max aspect ratio = 19.5931 OK.
    Minimum face area = 1.1577e-05. Maximum face area = 0.00177197.  Face area magnitudes OK.
    Min volume = 2.02597e-07. Max volume = 3.10095e-05.  Total volume = 1.752.  Cell volumes OK.
    Mesh non-orthogonality Max: 42.9364 average: 6.59459
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 1.19711 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

End

Then I ran the case and after a long time in "Time = 1" the following error is showed:

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;
}

No finite volume options present


SIMPLE: convergence criteria
    field p     tolerance 0.01
    field U     tolerance 0.001
    field "(k|epsilon|omega)"     tolerance 0.001


Starting time loop

Time = 1

#0  Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#1  Foam::sigFpe::sigHandler(int) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#2   in "/lib/x86_64-linux-gnu/libc.so.6"
#3  Foam::smoothSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#4  
 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
#5  
 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
#6  
 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
#7  
 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
#8  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#9  
 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
Floating point exception (core dumped)

Here I post information about my case.

U

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{
    fixedwall
    {
        type            zeroGradient;
    }
    inlet
    {
        type            fixedValue;
    value        uniform (0 0 0);
    }
    outlet
    {
        type            fixedValue;
    value        uniform (0 0 0);
    }
    sym
    {
        type        symmetry;    
    }
}

p

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 100000;

boundaryField
{
    fixedwall
    {
        type            zeroGradient;
    }
    inlet
    {
        type            fixedValue;
        value           uniform 100000;
    }
    outlet
    {
        type            fixedValue;
        value           uniform 0;
    }
    sym
    {
        type        symmetry;    
    }
}

k

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0.375;

boundaryField
{
    fixedwall
    {
        type            kqRWallFunction;
        value           uniform 0;
    }
    inlet
     {
        type            fixedValue;
        value           uniform 0.375;
    }
    outlet
    {
        type            fixedValue;
        value           uniform 14.855;
    }
    sym
    {
        type        symmetry;    
    }
}

epsilon

dimensions      [0 2 -3 0 0 0 0];

internalField   uniform 14.855;

boundaryField
{
    fixedwall
    {
        type            epsilonWallFunction;
        value           uniform 14.855;
    }    
    inlet
    {
        type            fixedValue;
        value           uniform 14.855;
    }
    outlet
    {
        type            fixedValue;
        value           uniform 14.855;
    }
    sym
    {
        type        symmetry;    
    }
}

nut

dimensions      [0 2 -1 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    fixedwall
    {
        type            nutkWallFunction;
        value           uniform 0;
    }    
    inlet
    {
        type            calculated;
        value           uniform 0;
    }
    outlet
    {
        type            calculated;
        value           uniform 0;
    }
    sym
    {
        type        symmetry;    
    }
}

transportProperties

transportModel  Newtonian;

nu              nu [ 0 2 -1 0 0 0 0 ] 1e-05;

CrossPowerLawCoeffs
{
    nu0             nu0 [ 0 2 -1 0 0 0 0 ] 1e-06;
    nuInf           nuInf [ 0 2 -1 0 0 0 0 ] 1e-06;
    m               m [ 0 0 1 0 0 0 0 ] 1;
    n               n [ 0 0 0 0 0 0 0 ] 1;
}

BirdCarreauCoeffs
{
    nu0             nu0 [ 0 2 -1 0 0 0 0 ] 1e-06;
    nuInf           nuInf [ 0 2 -1 0 0 0 0 ] 1e-06;
    k               k [ 0 0 1 0 0 0 0 ] 0;
    n               n [ 0 0 0 0 0 0 0 ] 1;
}

RASProperties

RASModel        kEpsilon;

turbulence      on;

printCoeffs     on;

ControlDict

application     simpleFoam;

startFrom       latestTime;

startTime       0;

stopAt          endTime;

endTime         500;

deltaT          1;

writeControl    timeStep;

writeInterval   10;

purgeWrite      5;

writeFormat     ascii;

writePrecision  6;

writeCompression off;

timeFormat      general;

timePrecision   6;

runTimeModifiable true;

fvSchemes

ddtSchemes
{
    default         steadyState;
}

gradSchemes
{
    default         Gauss linear;
}

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

laplacianSchemes
{
    default         Gauss linear limited 0.222;
}

interpolationSchemes
{
    default        linear;
    interpolate(U) linear;
}

snGradSchemes
{
    default         limited 0.222;
}

fluxRequired
{
    default         no;
    p               ;
}

fvSolution

solvers
{
    p
    {
        solver          GAMG;
        tolerance       1e-06;
        relTol          0.1;
        smoother        GaussSeidel;
        nPreSweeps      0;
        nPostSweeps     2;
        cacheAgglomeration on;
        agglomerator    faceAreaPair;
        nCellsInCoarsestLevel 10;
        mergeLevels     1;
    }

    "(U|k|epsilon|R|nuTilda)"
    {
        solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-05;
        relTol          0.1;
    }
}

SIMPLE
{
    nNonOrthogonalCorrectors 0;

    residualControl
    {
        p               1e-2;
        U               1e-3;
        "(k|epsilon|omega)" 1e-3;
    }
}

relaxationFactors
{
    fields
    {
        p               0.3;
    }
    equations
    {
        U               0.7;
        k               0.7;
        epsilon         0.7;
        R               0.7;
        nuTilda         0.7;
    }
}

I thought change U and p values... or change the patch type. Maybe the k, epsilon values are the problem... I don't know and before to change anything without knowing I'd like to hear your opinions to fix the problem. I'm here to learn and any help or advice is welcome.

Regards.

[betakv]

I have seen there an error, that is connected with the wrong definition of boundary conditions. Usually on inlet (in the case of U, k, epsilon) you are defining fixed value and on outlet zeroGradient or inletOutlet should be specified. For pressure you have to presribed on inlet zeroGradient and on outlet fixedValue.You can used also totalPressure for p and pressureDirectedInlet for Uin the case of inlet BC
Please check some tutorials and compared it with your case.

[alvariten]

I have seen there an error, that is connected with the wrong definition of boundary conditions. Usually on inlet (in the case of U, k, epsilon) you are defining fixed value and on outlet zeroGradient or inletOutlet should be specified. For pressure you have to presribed on inlet zeroGradient and on outlet fixedValue.You can used also totalPressure for p and pressureDirectedInlet for Uin the case of inlet BC
Please check some tutorials and compared it with your case.

Hi Vojtech,
Thanks for reply. I tried all you suggested. After to read many post I think the best option for my Bc's are:

Totalpressure (inlet) and fixedValue (outlet)
pressureInletOutletVelocity (inlet) and inletOutlet (outlet)

What do you think?

But my problem still appear... I tried to change the Numerical Schemes to 1st Order, I tried to change the Turbulence Model (Laminar, k-e...) even tried with solver pisoFoam and the same Bc's.

I checked pitzDaily tutorial because is similar to my problem. I caught case folders and changed the geometry and the respective patchfields but neither worked.

Always cashed in the first loop:

Time = 1

smoothSolver:  Solving for Ux, Initial residual = 0, Final residual = 0, No Iterations 1
smoothSolver:  Solving for Uy, Initial residual = 0, Final residual = 0, No Iterations 1
#0  Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#1  Foam::sigFpe::sigHandler(int) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#2   in "/lib/x86_64-linux-gnu/libc.so.6"
#3  Foam::GAMGSolver::scale(Foam::Field<double>&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#4  Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMatrix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#5  Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#6  Foam::fvMatrix<double>::solveSegregated(Foam::dictionary const&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
#7  Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
#8  
 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
#9  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#10  
 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
/home/alvaro/OpenFOAM/Engys/N2D_pisoFoam/solver_serial.run: line 30:  4371 Floating point exception(core dumped) $SOLVER -case $CASE 2>&1
      4372 Done                    | tee $LOG

It's strange to me that the residual values of velocity are 0, what this means?

What more could I do?

Cheers.

[betakv]

I think there is still an error in your BC. Can you post it?

[alvariten]

Hi Vojtech,

p

 dimensions [ 0 2 -2 0 0 0 0 ];
internalField uniform 1000.0;
boundaryField
{
    back
    {
        type empty;
    }

    front
    {
        type empty;
    }

    inlet
    {
        type totalPressure;
        p0 uniform 1000;
        value uniform 1000;
        rho none;
        psi none;
        U U;
        phi phi;
        gamma 1;
    }

    outlet
    {
        type fixedValue;
        value uniform 100;
    }

    sym
    {
        type symmetryPlane;
    }

    wall1
    {
        type zeroGradient;
    }

    wall2
    {
        type zeroGradient;
    }

}

U

dimensions [ 0 1 -1 0 0 0 0 ];
internalField uniform (0.0 0.0 0.0);
boundaryField
{
    back
    {
        type empty;
    }

    front
    {
        type empty;
    }

    inlet
    {
        type pressureInletOutletVelocity;
        value uniform ( 0 0 0);
    }

    outlet
    {
        type inletOutlet;
        value uniform (0 0 0);
        inletValue uniform (0 0 0);
    }

    sym
    {
        type symmetryPlane;
    }

    wall1
    {
        type fixedValue;
        value uniform ( 0 0 0);
    }

    wall2
    {
        type fixedValue;
        value uniform ( 0 0 0);
    }

}

And this show the terminal when I run the case (if if help)

Starting time loop

Time = 1

smoothSolver:  Solving for Ux, Initial residual = 1, Final residual = 0.314744, No Iterations 1000
smoothSolver:  Solving for Uy, Initial residual = 1, Final residual = 0.285886, No Iterations 1000
#0  Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#1  Foam::sigFpe::sigHandler(int) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#2   in "/lib/x86_64-linux-gnu/libc.so.6"
#3  Foam::GAMGSolver::scale(Foam::Field<double>&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#4  Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMatrix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#5  Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#6  Foam::fvMatrix<double>::solveSegregated(Foam::dictionary const&) in "/opt/openfoam230/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
#7  Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
#8  
 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
#9  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#10  
 in "/opt/openfoam230/platforms/linux64GccDPOpt/bin/simpleFoam"
Floating point exception (core dumped)

The main idea of the study is I have to set the pressure at the inlet and the outlet. And in any way I look for to know the velocity at inlet and outlet. What would you propose?

Thanks

[peravali]

hello alvaro,

I am having similar problem as you and my boundary conditions seems ok.
Were you able to find out the problem?

//surya