[OpenFOOL]

Hi folks,


I am still a bloody beginner and I think I need some help of you. Currently I am facing problems with a rhoSimpleFoam case. The simulation won't run (sigFpe after a few iterations) and I am quiet sure that I made some basic mistakes, but I can't find them. Originally the geometry is a bit more complex, but to make things not more complicated than necessary I made a simple case. In the end I want to simulate the transient case with turbulence and in parallel, for now just laminar and on a single core.

It's a simple pressure driven flow of nitrogen at 293K with a total pressure of 1113mBar at the inlet and a static pressure of 1013mBar (atmosphere) at the outlet. Now I want to know the velocity field behind the capillary. (see attached picture)



CheckMesh outputs just one fail:

***Concave cells (using face planes) found, number of cells: 30

The error message output: (I used the limitTemperature option, because I got negative initial temperatures)

/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  5.0                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
Build  : 5.0
Exec   : rhoSimpleFoam
Date   : May 11 2020
Time   : 13:10:09
Host   : "o2.box"
PID    : 8473
I/O    : uncollated
Case   : /home/leon/OpenFOAM/leon-5.0/run/CapillaryHead_Reduced_CFDONLINE
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 mesh for time = 0


SIMPLE: convergence criteria
    field p      tolerance 0.001
    field U      tolerance 1e-05
    field h      tolerance 0.0001

Reading thermophysical properties

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

Reading field U

Reading/calculating face flux field phi

Creating turbulence model

Selecting turbulence model type laminar
Selecting laminar stress model Stokes
No MRF models present

Creating finite volume options from "constant/fvOptions"

Selecting finite volume options model type limitTemperature
    Source: limitT
    - selecting all cells
    - selected 1062441 cell(s) with volume 2.90662e-06

Starting time loop

Time = 1e-06

smoothSolver:  Solving for Ux, Initial residual = 1, Final residual = 0.0739827, No Iterations 1
smoothSolver:  Solving for Uy, Initial residual = 1, Final residual = 0.0777189, No Iterations 2
smoothSolver:  Solving for Uz, Initial residual = 1, Final residual = 0.0755014, No Iterations 1
smoothSolver:  Solving for h, Initial residual = 0.512191, Final residual = 0.52304, No Iterations 1000
GAMG:  Solving for p, Initial residual = 1, Final residual = 0.00624987, No Iterations 4
GAMG:  Solving for p, Initial residual = 0.00244342, Final residual = 1.55703e-05, No Iterations 4
time step continuity errors : sum local = 4.17756e-05, global = -7.39803e-06, cumulative = -7.39803e-06
ExecutionTime = 41.59 s  ClockTime = 41 s

Time = 2e-06

smoothSolver:  Solving for Ux, Initial residual = 0.116653, Final residual = 0.0102574, No Iterations 1
smoothSolver:  Solving for Uy, Initial residual = 0.164785, Final residual = 0.0162303, No Iterations 1
smoothSolver:  Solving for Uz, Initial residual = 0.116716, Final residual = 0.0103955, No Iterations 1
smoothSolver:  Solving for h, Initial residual = 1, Final residual = 0.0105551, No Iterations 1
GAMG:  Solving for p, Initial residual = 0.919701, Final residual = 0.00886947, No Iterations 5
GAMG:  Solving for p, Initial residual = 8.3929e-06, Final residual = 6.02233e-07, No Iterations 2
time step continuity errors : sum local = 0.0203171, global = -0.00860199, cumulative = -0.00860938
ExecutionTime = 43.7 s  ClockTime = 43 s

Time = 3e-06

smoothSolver:  Solving for Ux, Initial residual = 0.140316, Final residual = 0.00638256, No Iterations 1
smoothSolver:  Solving for Uy, Initial residual = 0.126721, Final residual = 0.0102169, No Iterations 1
smoothSolver:  Solving for Uz, Initial residual = 0.13993, Final residual = 0.00640871, No Iterations 1
smoothSolver:  Solving for h, Initial residual = 0.996934, Final residual = 0.0110586, No Iterations 1
#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::sigFpe::sigHandler(int) at ??:?
#2  ? in "/lib64/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 at ??:?
#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 at ??:?
#5  Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
#6  Foam::fvMatrix<double>::solveSegregated(Foam::dictionary const&) at ??:?
#7  Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
#8  Foam::fvMatrix<double>::solve() at ??:?
#9  ? at ??:?
#10  __libc_start_main in "/lib64/libc.so.6"
#11  ? at /home/abuild/rpmbuild/BUILD/glibc-2.26/csu/../sysdeps/x86_64/start.S:122
Floating point exception (core dumped)

My pressure boundary conditions are as follows:

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 101325;

boundaryField
{
    CylIn
    {
        type            zeroGradient;
    }
    
    Cone
    {
        type            zeroGradient;
    }

    ConeIn
    {
        type            zeroGradient;
    }

    CylInCone
    {
        type            zeroGradient;
    }

    CylOutCone
    {
        type            zeroGradient;
    }

    HeadWalls
    {
        type            zeroGradient;
    }

    ShotWall
    {
        type            zeroGradient;
    }
    
    Inlet
    {
        type            totalPressure;
        p0              uniform 111325;
        gamma           1;
        value           uniform 111325;
    } 
    Outlet
    {
        type            fixedValue;
        value           uniform 101325;
    }
}

My velocity BCs look like this:

FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform (0 0 0);

boundaryField
{
    CylIn
    {
        type            noSlip;
    }
    
    Cone
    {
        type            noSlip;
    }

    ConeIn
    {
        type            noSlip;
    }

    CylInCone
    {
        type            noSlip;
    }

    CylOutCone
    {
        type            noSlip;
    }

    HeadWalls
    {
        type            noSlip;
    }

    ShotWall
    {
        type            noSlip;
    }
    
    Inlet
    {
        
        type            pressureInletOutletVelocity;
        value           uniform (0 0 0);
    } 
    
    Outlet
    {
        type            inletOutlet;
        value           $internalField;
        inletValue      uniform (0 0 0);
    }
}

My temperature BCs:

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 1 0 0 0];

internalField   uniform 293;

boundaryField
{
    CylIn
    {
        type            zeroGradient;
    }
    
    Cone
    {
        type            zeroGradient;
    }

    ConeIn
    {
        type            zeroGradient;
    }

    CylInCone
    {
        type            zeroGradient;
    }

    CylOutCone
    {
        type            zeroGradient;
    }

    HeadWalls
    {
        type            zeroGradient;
    }

    ShotWall
    {
        type            zeroGradient;
    }
    
    Inlet
    {
        
        type            fixedValue;
        value           uniform 293;
    } 
    Outlet
    {
        type            inletOutlet;
        value           $internalField;
        inletValue      $internalField;
    }
}

My thermophysicalProperties:

FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      thermophysicalProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

mixture
{
    specie
    {
        molWeight   28.013;
    }
    thermodynamics
    {
        Cp          1040;
        //Hf          22e-6;
        Hf          0;
    }
    transport
    {
        mu          17.58e-06;
        Pr          0.8;
    }
}

Anything completely wrong with those settings?
Maybe it's my fvSchemes or fvSolution file? I have to admit with those settings I am most unsecure. Currently I am trying to get more knowledge about them, but it's quiet hard.

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

ddtSchemes
{
    default         steadyState;
}

gradSchemes
{
    default         Gauss linear;   
}

divSchemes
{
    default         Gauss linear;
}

laplacianSchemes
{
    default         Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         corrected;
}

And fvSolution:

FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    p
    {
        solver          GAMG;
        tolerance       1e-06;
        relTol          0.01; 
        smoother    GaussSeidel;
        nPreSweeps    0;
        nPostSweeps    2;
        cacheAgglomeration    on;
        agglomerator    faceAreaPair;
        nCellsInCoarsestLevel    10;
        mergeLevels    1;
    }

    pFinal
    {
        $p;
        relTol          0;
    }

    "(rho|U|h)"
    {
        solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-05;
        relTol          0.1;
    }

    "(rho|U|h)Final"
    {
        $U;
        tolerance       1e-05;
        relTol          0;
    }
}

SIMPLE
{
    nNonOrthogonalCorrectors 1;
    residualControl
    {
        p               1e-3;
        U               1e-5;
        h               1e-4;

    }
}

relaxationFactors
{
    fields
    {
        p               0.1;
    }
    equations
    {
        U               0.7;
        h               0.2;
    }
}

Could you please give me a hint or lead me in the right direction? I would really appreciate it, because I'm quiet desperate.





Best regards


Leon

[cfdcheckers]

Hi,did you manage to get past this? What was wrong?

I have a similarish case I'm struggling with: Correct BCs for known outlet conditions and unknown inlet conditions.
If you did manage to get a grip on your case, can you give me some hints?

[Sakun]

Hello guys,

I am having the same issue as well.

Did you all managed to solve the issue ? highly appreciate if you guys can help.