[Yann]

Hello Mohd Shaeq,

There is indeed some bad math happening, and it seems related to the turbulence model (according to the error message mentioning it, and the fact the error happens when the solver tries to solve epsilon)

This could be caused by different things: boundary conditions, numerical setup, maybe mesh, ...

Regarding your second issue, I am not familiar with the processes you are simulating so I am not sure I can help. How is penetration length defined for liquids and gases?

Regards,
Yann

[MohdShaeq]

Hello Yann,

I was able to make rhoReactingFoam run by making changes to the temperature boundary condition. I made a comparison for two turbulence models, viz. RAS and LES. The simulation ran a lot faster for LES in comparison to RAS. What could be the reason for this? After running smoothly and steadily for the first 38 timesteps, the simulation crashes, however, in the 39th one with the following error:-

Courant Number mean: 5.99255e-05 max: 120.942
Time = 3.9e-06

diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
PIMPLE: iteration 1
smoothSolver:  Solving for Ux, Initial residual = 0.0237574, Final residual = 0.00161816, No Iterations 2
smoothSolver:  Solving for Uy, Initial residual = 0.00593231, Final residual = 0.000405769, No Iterations 2
smoothSolver:  Solving for Uz, Initial residual = 9.06636e-06, Final residual = 3.77099e-07, No Iterations 2
[5] #0  Foam::error::printStack(Foam::Ostream&) at ??:?
[5] #1  Foam::sigFpe::sigHandler(int) at ??:?
[5] #2  ? in /lib64/libc.so.6
[5] #3  Foam::symGaussSeidelSmoother::smooth(Foam::word const&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::Field<double> const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, unsigned char, int) at ??:?
[5] #4  Foam::symGaussSeidelSmoother::smooth(Foam::Field<double>&, Foam::Field<double> const&, unsigned char, int) const at ??:?
[5] #5  Foam::smoothSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
[5] #6  Foam::fvMatrix<double>::solveSegregated(Foam::dictionary const&) at ??:?
[5] #7  Foam::fvMatrix<double>::solveSegregatedOrCoupled(Foam::dictionary const&) at ??:?
[5] #8  Foam::fvMesh::solve(Foam::fvMatrix<double>&, Foam::dictionary const&) const at ??:?
[5] #9  ? at ??:?
[5] #10  __libc_start_main in /lib64/libc.so.6
[5] #11  ? at ??:?
[iflw019:1272589:0:1272589] Caught signal 8 (Floating point exception: tkill(2) or tgkill(2))
==== backtrace (tid:1272589) ====
 0  /lib64/libucs.so.0(ucs_handle_error+0x2dc) [0x7efd92658e4c]
 1  /lib64/libucs.so.0(+0x2c02c) [0x7efd9265902c]
 2  /lib64/libucs.so.0(+0x2c2da) [0x7efd926592da]
 3  /lib64/libc.so.6(gsignal+0x10f) [0x7efdaf568acf]
 4  /opt/OpenFOAM/OpenFOAM-v1912/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZN4Foam22symGaussSeidelSmoother6smoothERKNS_4wordERNS_5FieldIdEERKNS_9lduMatrixERKS5_RKNS_10FieldFieldIS4_dEERKNS_8UPtrListIKNS_17lduInterfaceFieldEEEhi+0x2ed) [0x7efdb0a0c82d]
 5  /opt/OpenFOAM/OpenFOAM-v1912/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZNK4Foam22symGaussSeidelSmoother6smoothERNS_5FieldIdEERKS2_hi+0x3b) [0x7efdb0a0ca7b]
 6  /opt/OpenFOAM/OpenFOAM-v1912/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZNK4Foam12smoothSolver5solveERNS_5FieldIdEERKS2_h+0x641) [0x7efdb0a011f1]
 7  /opt/OpenFOAM/OpenFOAM-v1912/platforms/linux64GccDPInt32Opt/lib/libfiniteVolume.so(_ZN4Foam8fvMatrixIdE15solveSegregatedERKNS_10dictionaryE+0x178) [0x7efdb7422e28]
 8  /opt/OpenFOAM/OpenFOAM-v1912/platforms/linux64GccDPInt32Opt/lib/libfiniteVolume.so(_ZN4Foam8fvMatrixIdE24solveSegregatedOrCoupledERKNS_10dictionaryE+0x37d) [0x7efdb6d8ca0d]
 9  /opt/OpenFOAM/OpenFOAM-v1912/platforms/linux64GccDPInt32Opt/lib/libfiniteVolume.so(_ZNK4Foam6fvMesh5solveERNS_8fvMatrixIdEERKNS_10dictionaryE+0xf) [0x7efdb6d35bbf]
10  rhoReactingFoam() [0x433ada]
11  /lib64/libc.so.6(__libc_start_main+0xe5) [0x7efdaf554d85]
12  rhoReactingFoam() [0x439e4e]

Based on my limited understanding of diagnosing errors, I think that this is related to the solver settings. Please correct me if I am wrong.

The fvSolution file is as follows:-

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v1912                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    p
    {
        solver           GAMG;

        smoother         GaussSeidel;

        tolerance       1e-6;
        relTol          0.01;
    }

    pFinal
    {
        $p;
        relTol          0;
    }

    "pcorr.*"
    {
        $p;
        tolerance       1e-2;
        relTol          0;
    }

    "(rho|U|h|k|epsilon|omega|Yi)"
    {
        solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-06;
        relTol          0.1;
    }

    "(rho|U|h|k|epsilon|omega|Yi)Final"
    {
        $U;
        relTol          0;
    }

}

PIMPLE
{
momentumPredictor   yes;
    transonic           no;
    nOuterCorrectors    3;
    nCorrectors         1;
    nNonOrthogonalCorrectors 0;

    pMaxFactor          1.2;
    pMinFactor          0.8;
}

relaxationFactors
{
    equations
    {
        "(U|h|k|epsilon|omega).*" 1;
    }
}


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

The fvSchemes file is as follows:/

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v1912                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default         Euler;
}

gradSchemes
{
    default      cellLimited Gauss linear 0.5;
    grad(U)      faceLimited Gauss linear 0.5;
}

divSchemes
{
    default         none;

    div(phi,U)      Gauss linearUpwind grad(U);
    div(phi,h)      Gauss linearUpwind grad(h);
    div(phi,K)      Gauss linear;
    div(meshPhi,p)  Gauss linear;
    div(phi,k)      Gauss upwind;
    div(phi,epsilon) Gauss upwind;
    div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
    div(phi,Yi_h)   Gauss upwind;
}

laplacianSchemes
{
    default     Gauss linear limited 0.5;
    //default         Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         limited 0.5;
    //default         corrected;
}

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

Apropos the second issue:-
Liquid Penetration Length: The distance travelled axially from 95 % of
the mass fraction of the liquid phase from the exit of the nozzle.

Vapour Penetration Length: The distance traveled axially from 0.1 %
of the mass fraction of the vapour phase, originated by the evaporation
of the liquid phase injected, from the exit of the nozzle.

Kind regards,
Mohd Shaeq