[Shibi]

Hello to all,

I am trying to simulate a 2D simple shear flow case with OpenFOAM using simpleFOAM. Afterwards, I would like to use the steady-state velocity field in some pimpleFoam simulations.

I am having a problem with simpleFoam. I get complete convergence of the x-component of velocity, however, I cannot converge the pressure and the z-component. I have run out of ideas, and would appreciate some help!

The dictionaries I am using are:

convertToMeters 0.1;

vertices
(
    (0 0 0)
    (1 0 0)
    (1 0.25 0)
    (0 0.25 0)
    (0 0 0.25)
    (1 0 0.25)
    (1 0.25 0.25)
    (0 0.25 0.25)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (40 10 10) simpleGrading (1 1 1)
);

edges
(
);

boundary
(
    top
    {

        type patch;
        faces
        (
            (4 5 6 7)
            
        );
    }

    bottom
    {

        type patch;
        faces
        (
           (0 3 2 1)
            
        );
    }
    wall1
    {
        type cyclic;
        neighbourPatch wall2;
        faces
        (   
             (2 6 5 1)
        );
    }

    wall2
    {
        type cyclic;
        neighbourPatch wall1;
        faces
        (   
            (0 4 7 3)
        );
    }
    
    emptyFaces
    {
        type empty;
        faces
        (   
           (1 5 4 0)
            (3 7 6 2) 
        );
    }
);

mergePatchPairs
(
);

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2012                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    location    "0";
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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


internalField   uniform (0 0 0);

boundaryField
{
    top
    {
        type            fixedValue;
        value           uniform (1 0 0);
    }
    bottom
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }
    "(wall.*)"
    {
       type                      cyclic;
    }
   emptyFaces
    {
        type            empty;
    }
}


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

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2012                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 0;

boundaryField
{
    "(.*)"
    {
        type    zeroGradient;
    }

    "(wall.*)"
    {
       type     cyclic;
    }

    emptyFaces
    {
        type            empty;
    }
}

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

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2012                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default         steadyState;
}

gradSchemes
{
    default         Gauss linear;
}

divSchemes
{
    default         none;
    div(phi,U)      Gauss linear;
    div((nuEff*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
    default         Gauss linear uncorrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         uncorrected;
}

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

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2012                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    p
    {
        /*solver          GAMG;
        smoother        DIC;
        tolerance       1e-6;
        relTol          0.01;*/
        solver          PCG;
        preconditioner  DIC;
        tolerance       1e-06;
        relTol          0.1;
    }

    "(U|sigma)"
    {
        /*solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-6;
        relTol          0.1;*/
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-06;
        relTol          0.1;
    }

    pFinal
    {
        $p;
        relTol          0;
    }

    "(U|sigma)Final"
    {
        $U;
        relTol          0;
    }
}

SIMPLE
{
    nNonOrthogonalCorrectors 0;
    pRefCell 0;
    pRefValue 0;
    residualControl
    {
        p               1e-6;
        U                1e-6;
    }
}


relaxationFactors
{
    fields
    {
        p   0.3;
    }

    equations
    {
        U   0.7;
    }
}

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

[keitaro7_14]

Try to fix the value of the pressure in a cell or in a whole patch of a boundary.

Like here:

https://github.com/OpenFOAM/OpenFOAM...pipeCyclic/0/p

[Shibi]

Originally Posted by keitaro7_14

Try to fix the value of the pressure in a cell or in a whole patch of a boundary.

Like here:

https://github.com/OpenFOAM/OpenFOAM...pipeCyclic/0/p

Hi,


Thank you for the reply. However, this is already being made in the Simple subdict with the parameters

    
pRefCell 0;
pRefValue 0;

I can get it to converge it I put a very small value for pRefValue, e.g., 0.1. However I do not understand why...