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-   -   rhoCentralFoam boundary issues with custom local time stepping (http://www.cfd-online.com/Forums/openfoam-solving/97561-rhocentralfoam-boundary-issues-custom-local-time-stepping.html)

laurensvd February 20, 2012 11:15

rhoCentralFoam boundary issues with custom local time stepping
 
I have an axisymmetric problem which I am simulating with rhoCentralFoam and a k-Omega-SST turbulence model. At my outlet I have anomalies (see an example of the pressure distribution in the image below).

The reason for these anomalies is related to me using a local time stepping method which I got from this forum (http://www.cfd-online.com/Forums/ope...ntralfoam.html). I dont have the anomalies in the original code without the local time stepping. Now, I would still like to have the local time stepping since I am only interested in the steady state solution and my calculations take way too long otherwise. Can anyone suggest some changes to get rid of these numerical errors?

My patches are defined as follows (not mentioning my model patches):
Code:

patch: frontAndBack
  all wedge

patch: symmetryLine
    all zeroGradient

patch: outlet
    scalar        k        inletOutlet
    scalar        alphat        calculated
    scalar        p        fixedValue
    scalar        T        fixedValue
    scalar        mut        calculated
    scalar        omega        inletOutlet
    vector        U        zeroGradient

patch: atmosphere
    scalar        k        fixedValue
    scalar        alphat        calculated
    scalar        p        slip
    scalar        T        zeroGradient
    scalar        mut        calculated
    scalar        omega        fixedValue
    vector        U        slip

patch: inlet
    scalar        k        fixedValue
    scalar        alphat        calculated
    scalar        p        zeroGradient
    scalar        T        zeroGradient
    scalar        mut        calculated
    scalar        omega        fixedValue
    vector        U        fixedValue

My fvSolution is:
Code:

solvers
{
    "(rho|rhoU|rhoE)"
    {
        solver          diagonal;
    }

    U
    {
        solver          smoothSolver;
        smoother        GaussSeidel;
        nSweeps        2;
        tolerance      1e-12;
        relTol          0;

    }

    "(e|omega|k|R|epsilon|h)"
    {
        $U;
        tolerance      1e-10;
        relTol          0;
    }
   
    p
    {
        solver GAMG;
        tolerance 1e-08;   
        relTol 0.01;   
        smoother GaussSeidel;   
        cacheAgglomeration off;   
        nCellsInCoarsestLevel 20;   
        agglomerator faceAreaPair;   
        mergeLevels 1;
    }

}

and my fvSchemes:
Code:

fluxScheme      Tadmor;

ddtSchemes
{
    default        localEuler rDeltaT;

}

gradSchemes
{
    default cellLimited leastSquares 1;
}

divSchemes
{
    default none;
    div(tauMC) Gauss linear;
    div(phi,k) Gauss Gamma 1;
    div(phi,omega) Gauss Gamma 1;
}

laplacianSchemes
{
    default Gauss linear corrected;
}

interpolationSchemes
{
    default linear;
    reconstruct(rho) Gamma 1;
    reconstruct(U) GammaV 1;
    reconstruct(T) Gamma 1;
}

snGradSchemes
{
    default corrected;
}

fluxRequired
{
    default no;   
    p;
}

http://i40.tinypic.com/w8xbww.png


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