[Clau.77]

Hey guys!


i have a multi region case in OF8 and i am having trouble with my fluid.

To keep it simple i am using steadyState and laminar flow.
The solver log looks like this:

/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  8
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
Build  : 8
Exec   : chtMultiRegionFoam
Date   : May 08 2021
Time   : 19:20:03
Host   : "login02.css.lan"
PID    : 51958
I/O    : uncollated
Case   : /bigwork/nhkfclan/Test_Merci
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create fluid mesh for region Luft for time = 0

Create solid mesh for region Form for time = 0

Create solid mesh for region Schokolade for time = 0

*** Reading fluid mesh thermophysical properties for region Luft

    Adding to thermoFluid

Selecting thermodynamics package 
{
    type            heRhoThermo;
    mixture         pureMixture;
    transport       const;
    thermo          hConst;
    equationOfState perfectGas;
    specie          specie;
    energy          sensibleEnthalpy;
}

    Adding to rhoFluid

    Adding to UFluid

    Adding to phiFluid

    Adding to gFluid

    Adding to hRefFluid

    Adding to pRefFluid

    Adding to ghFluid

    Adding to ghfFluid

    Adding to turbulenceFluid

Selecting turbulence model type laminar
Selecting laminar stress model Stokes
    Adding to thermophysicalTransport

Selecting thermophysical transport type laminar
Selecting default laminar thermophysical transport model Fourier
    Adding to reactionFluid

Combustion model not active: combustionProperties not found
Selecting combustion model none
    Adding to radiationFluid

Radiation model not active: radiationProperties not found
Selecting radiationModel none
    Adding to KFluid

    Adding to dpdtFluid

    Adding to fieldsFluid

    Adding MRF

No MRF models present

    Adding fvOptions

*** Reading solid mesh thermophysical properties for region Form

    Adding to thermos

Selecting thermodynamics package 
{
    type            heSolidThermo;
    mixture         pureMixture;
    transport       constIso;
    thermo          eConst;
    equationOfState rhoConst;
    specie          specie;
    energy          sensibleInternalEnergy;
}

    Adding to radiations

Radiation model not active: radiationProperties not found
Selecting radiationModel none
    Adding fvOptions

*** Reading solid mesh thermophysical properties for region Schokolade

    Adding to thermos

Selecting thermodynamics package 
{
    type            heSolidThermo;
    mixture         pureMixture;
    transport       constIso;
    thermo          eConst;
    equationOfState rhoConst;
    specie          specie;
    energy          sensibleInternalEnergy;
}

    Adding to radiations

Radiation model not active: radiationProperties not found
Selecting radiationModel none
    Adding fvOptions


PIMPLE: Region Luft
PIMPLE: No convergence criteria found


PIMPLE: Region Form
PIMPLE: No convergence criteria found


PIMPLE: Region Schokolade
PIMPLE: No convergence criteria found


PIMPLE: Operating solver in steady-state mode with 1 outer corrector
PIMPLE: Operating solver in SIMPLE mode


Region: Luft Courant Number mean: 314.33656 max: 7014.9304
Region: Form Diffusion Number mean: 0.10103954 max: 261.63834
Region: Schokolade Diffusion Number mean: 101.25719 max: 251280.78
deltaT = 3.979466e-05
Region: Luft Courant Number mean: 0.012508916 max: 0.27915677
Region: Form Diffusion Number mean: 4.0208341e-06 max: 0.010411809
Region: Schokolade Diffusion Number mean: 0.0040294954 max: 9.9996333
deltaT = 3.979466e-05
Time = 3.97947e-05


Solving for fluid region Luft
DILUPBiCGStab:  Solving for Ux, Initial residual = 1, Final residual = 4.1108316e-09, No Iterations 2
DILUPBiCGStab:  Solving for Uy, Initial residual = 1, Final residual = 2.4053866e-08, No Iterations 2
DILUPBiCGStab:  Solving for Uz, Initial residual = 1, Final residual = 7.1445854e-08, No Iterations 2
DILUPBiCGStab:  Solving for h, Initial residual = 1, Final residual = 5.3058713e-08, No Iterations 3
Min/max T:284.67219 291.08218

I know that after that step something with p_rgh should be next, but then i am just getting a long error message which says floating point exception at the end. So I guess there is a problem with p_rgh or could it be something else? I know that it means, that something is devided by zero.



In the 0 directory for the fluid (air) i use fixedFluxPressure (and fixedValue at the outlet) for p_rgh and calculate for p. Both internalFields are 1e5.



the fluid is standard air, here the thermophysical properties:

thermoType
{
    type              heRhoThermo;  
    mixture         pureMixture;
    transport       const; 
    thermo          hConst;
    equationOfState perfectGas;
    specie          specie;
    energy          sensibleEnthalpy;
}


mixture 
{
    specie
    {
        //nMoles        1;
        molWeight   28.9;
    }
    thermodynamics
    {
        Cp          1000;
        Hf          0;
    }
    transport
    {
        mu          1.8e-05;
        Pr          0.7;   
    }
}

fvSchemes:

ddtSchemes
{
    default         steadyState;
}

gradSchemes
{
    default         Gauss linear;
}

divSchemes
{
    default         none;

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

laplacianSchemes
{
    default         Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         corrected;
}
wallDist
{
method        meshWave;
}

solvers
{

    rho
    {
        solver          diagonal;
    }

    rhoFinal
    {
        $rho;
    }

    p_rgh
    {
        solver           GAMG;
        smoother         symGaussSeidel;
        tolerance        1e-7;
        relTol           0.01;
    }

    p_rghFinal
    {
        $p_rgh;
        relTol           0;
    }

    
    p
    {
        solver           GAMG;
        smoother         symGaussSeidel;
        tolerance        1e-3;
        relTol           0.01;
    }

    p_Final
    {
        $p;
        relTol           0;
    }


    "(U|h|epsilon|omega)"
    {
        solver           PBiCGStab;
        preconditioner   DILU;
        tolerance        1e-7;
        relTol           0.1;
    }

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

PIMPLE
{
    momentumPredictor   yes;
}

relaxationFactors
{
    fields
    {
    p_rgh          0.7;
    p_rghFinal  0.3;
    rho         1;
    rhoFinal    0.1;
    }       

 equations
    {
        h              0.3;
    hFinal           0.3;
        U              0.1;
    UFinal           0.1;
    k            0.1;
    //omega        0.1;
    //epsilon        0.1;
    }
}

I played around with the fvSolution and fvSchemes but the error doesn't go away.


Does somebody have an idea where this error might come from and how to fix it? I would appreciate some help, I have been stuck with this error for days.



Also, let me know if I forgot to give important information.


Thanks!

[Clau.77]

Update:
it's a problem with the steadyState, different ddtSchemes work. But i still don't understand why