[Werne]

Hello,

I'm trying to simulate the flow in a conical annular gap with a rotating inner wall for my masters thesis. I'm using rhoSimpleFoam.

My Problem is, that I can't get a converged solution. Even after 100.000 Iterations the pressure continues to rise slowly.

Here are my boundary conditions, fvSolution and fvSchemes:

| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.2                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform (0 0 0);

boundaryField
{
    INLET
    {
        type            flowRateInletVelocity;
        massFlowRate    constant 0.0038;    //0.004167
        value           uniform (0 0 0);  
    }

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

   SYM_1_OBEN
    {
        type            cyclicAMI;
    }

    SYM_1_UNTEN
    {
        type            cyclicAMI;
    }

    SYM_2_OBEN
    {
        type            cyclicAMI;
    }

    SYM_2_UNTEN
    {
        type            cyclicAMI;
    }

    MOVINGWALL_OBEN
    {
        type            rotatingWallVelocity;
    origin        (0 0 0);
    axis        (1 0 0);
    omega        838;
    }

    MOVINGWALL_UNTEN
    {
        type            rotatingWallVelocity;
    origin        (0 0 0);
    axis        (1 0 0);
    omega        838;
    }

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

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

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

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

    KEIL
    {
        type            slip;
    }

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

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

}

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.2                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 320000;

boundaryField
{
    INLET
    {
    type        zeroGradient; 
    }

    OUTLET
    {
        type            fixedValue;
    value        uniform 220000;
    }

    SYM_1_OBEN
    {
        type            cyclicAMI;
    }

    SYM_1_UNTEN
    {
        type            cyclicAMI;
    }

    SYM_2_OBEN
    {
        type            cyclicAMI;
    }

    SYM_2_UNTEN
    {
        type            cyclicAMI;
    }

    MOVINGWALL_OBEN
    {
        type            zeroGradient;
    }

    MOVINGWALL_UNTEN
    {
        type            zeroGradient;
    }

    BOHRUNG
    {
        type            zeroGradient;
    }

    WALL_OBEN
    {
        type            zeroGradient;
    }

    WALL_UNTEN
    {
        type            zeroGradient;
    }

    PLENUMWALL
    {
        type            zeroGradient;
    }

    KEIL
    {
        type            zeroGradient;
    }

    GAP_S
    {
        type            zeroGradient;
    }

    GAB_W
    {
        type            zeroGradient;
    }
}

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.2                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 1 0 0 0];

internalField   uniform 360;

boundaryField
{
    INLET
    {
        type            fixedValue;
        value           $internalField;
    }

    OUTLET
    {
        type            inletOutlet;
    inletValue    $internalField;
    value        $internalField;
    }

    SYM_1_OBEN
    {
        type            cyclicAMI;
    }

    SYM_1_UNTEN
    {
        type            cyclicAMI;
    }

    SYM_2_OBEN
    {
        type            cyclicAMI;
    }

    SYM_2_UNTEN
    {
        type            cyclicAMI;
    }

    MOVINGWALL_OBEN
    {
        type            zeroGradient;
    }

    MOVINGWALL_UNTEN
    {
        type            zeroGradient;
    }

    BOHRUNG
    {
        type            zeroGradient;
    }

    WALL_UNTEN
    {
        type            fixedValue;
        value           $internalField;
    }

    WALL_OBEN
    {
        type            fixedValue;
        value           $internalField;
    }

    PLENUMWALL
    {
        type            zeroGradient;
    }

    KEIL
    {
        type            zeroGradient;
    }

    GAP_S
    {
        type            zeroGradient;
    }

    GAB_W
    {
        type            zeroGradient;
    }
}

fvSolution:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.2                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
 

   p
    {
    solver GAMG;
    tolerance 1e-7;   //1e-8
    relTol 0.05;
    smoother GaussSeidel;
    nPreSweeps 0;
    nPostSweeps 2;
    cacheAgglomeration on;
    agglomerator faceAreaPair;
    nCellsInCoarsestLevel 100;
    mergeLevels 1;
    }

  U
   {
        solver          smoothSolver;
        smoother        GaussSeidel;
        nSweeps         2;
        tolerance       1e-07;   ////1e-08
        relTol          0.01;
    }  

    h
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-7;   //1e-09
        relTol          0.1;
    }

    "(k|omega)" 
    {
        $U;
        tolerance       1e-07;
        relTol          0.1;
    }    
 
}

SIMPLE
{
    nNonOrthogonalCorrectors 2;
    rhoMin          rhoMin [ 1 -3 0 0 0 ] 1.5;
    rhoMax          rhoMax [ 1 -3 0 0 0 ] 7;
  //  transonic    true;

    residualControl
    {
        p               1e-6;        
        U               1e-6;        
        h               1e-6;        

        // possibly check turbulence fields
           "(k|epsilon|omega)" 1e-6;    
    }
}

relaxationFactors
{
    fields
    {
        p               0.3; //0.1
        rho             0.005; //0.05
    }
    equations
    {
        U               0.7; //0.7
        k        0.7; //0.7
        omega        0.7; //0.7
        h               0.7; //0.7
    }
}

fvSchemes:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.2                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default         steadyState;
}

gradSchemes
{
    default         Gauss linear;//cellLimited Gauss linear 1.0;    // Gauss linear;
}

divSchemes
{
    default     bounded Gauss upwind;
    div(phi,U)       bounded Gauss upwind;//bounded Gauss upwind;
    div((muEff*dev2(T(grad(U))))) Gauss linear;
    div(phi,e)       bounded Gauss upwind;
    div(phi,k)       bounded Gauss upwind;
    div(phi,omega)       bounded Gauss upwind;
    div(phi,Ekp)     bounded Gauss upwind;
}

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

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default          corrected;  //limited 0.5;
}

fluxRequired
{
    default         no;
    p               ;
}


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

I have attached a picture of the development of the pressure in my simulation. As you can see, it rises swiftly up to a certain point and aufterwards it slows down. However, it continues to rise, no matter how long I let the simulation run.

I really hope, that someone can give me any hints, what I can do to stabilize my solution.

Thank you in advance!

If you need any additional information, feel free to ask

edit: One problem that I've found is, that the enthalpy is converging very slowly. I've attached a gnuplot graph with my residuals. Could this be the cause of my problems? If so, what can I do about it?