CFD Online Discussion Forums - Problem in fvschemes divSchemes cannot use Gauss linearUpwind

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- - Problem in fvschemes divSchemes cannot use Gauss linearUpwind (https://www.cfd-online.com/Forums/openfoam-bugs/62534-problem-fvschemes-divschemes-cannot-use-gauss-linearupwind.html)

how do your results compare to measurements? are you under or over predicting?

In my case I over predict from 10 to 20 degrees

hi all

I noticed that both in both tutorial cases and posted fvschemes there is always

Code:

div(R) Gauss linear;

Is that because there is no flux (phi = rho U) in that term and should it be left like this?

I tried

Code:

div(R)          Gauss limitedLinear 1;

div(R)          Gauss QUICK;

div(R)          Gauss MUSCL;

and it gave me similar results without any problems/errors.

thanks
Uli

Hi! It is for other turbulence model where you use Reynolds stress

Thanks for your reply.

So using a k-Epsilon model does not involve R? But how is it possible that I get different results after switching the scheme for div(R)?

You wrote you get the SAME results. You can easily check which schemes you solver uses, just set "default none;", and you will get errors until you define all schemes.

hi, sorry for the late reply.

I wrote "similar" results since the plots are slightly different. I removed the schemes and it still worked, thanks for your help.

Hi all,

I have to simulate the case of time varying BC 'uniformValue' for p and T

I tried various ways listed here and also from other open-sources, for schemes and solvers, to solve the 'p' with rhoSimpleFoam.

whatever may be the conditions applied, the solver is unable to run after third time-step. here I am posting my schemes and solvers. I am thinking that the problem is with these files only because I have cross-checked the p, T and U files and am also able to run 'rhoPimpleFoam' successfully.

Please let me know what went wrong.

Code:

/*--------------------------------*- 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         cellLimited leastSquares 1;//Gauss linear;

//    grad(U)         Gauss linear;

    grad(P)         Gauss linear;

}



divSchemes

{

    default         none;//Gauss linear corrected; //

    div(phi,U)      bounded Gauss upwind;

    div((muEff*dev2(T(grad(U))))) Gauss linear;

    div(phi,e)      bounded Gauss upwind;

    div(phi,h)      bounded Gauss upwind;

    div(phi,epsilon) bounded Gauss upwind;

    div(phi,omega)   bounded Gauss upwind;

    div(phi,k)      bounded Gauss upwind;

    div(phi,K)      bounded Gauss upwind;

    div(phi,Ekp)    bounded Gauss upwind;

    div(phid,p)     Gauss upwind;//bounded Gauss upwind;

    div(U,p)      bounded Gauss upwind;

}



laplacianSchemes

{

    default         Gauss linear orthogonal;//Gauss linear corrected;

//    laplacian(muEff,U) Gauss linear corrected;

//    laplacian(alphaEff,e) Gauss linear corrected;

//    laplacian(alphaEff,h) Gauss linear corrected;

//    laplacian((rho*(1|A(U))),p) Gauss linear corrected;

//    laplacian((rho|A(U)),p) Gauss linear corrected;

//    laplacian((rho*rAU),p) Gauss linear corrected;

//    laplacian(DepsilonEff,epsilon) Gauss linear corrected;

//   laplacian(DomegaEff,omega) Gauss linear corrected;

//    laplacian(DkEff,k) Gauss linear corrected;

//   laplacian(1,p) Gauss linear corrected;

}



interpolationSchemes

{

    default         linear;

    div(U,p)        upwind phi;

}



snGradSchemes

{

    default         corrected;

}



fluxRequired

{

    default         no;

    p               ;

}





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

Code:

/*--------------------------------*- 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         PCG;//GAMG;//

        preconditioner  none;//DIC;//FDIC;//GAMG;//diagonal;//

        agglomerator    faceAreaPair;

       tolerance       1e-07;

        relTol          0;//0.05;

        smoother        GaussSeidel;

        cacheAgglomeration true;//off;

        nCellsInCoarsestLevel 10;//20;

        mergeLevels     1;

    } //temperoraily not using 





    "(U|e|h|R|k|epsilon|omega)" //"(U|p|e|h|R|k|epsilon|omega)"

    {

        solver          smoothSolver;//solver          diagonal;//

        smoother        GaussSeidel;

        nSweeps         2;

        tolerance       1e-06;

//        relTol          0; //0.1;

//        solver          PBiCG;

//        preconditioner  DILU;

//        tolerance       1e-06;

//        relTol          0; //0.1;

    }



//    "(k|epsilon|omega)"

//    {

//        $U;

//        tolerance       1e-05;

//        relTol          0; //0.1;

//    }

}



SIMPLE

{

    nNonOrthogonalCorrectors 0;

    rhoMin          rhoMin [ 1 -3 0 0 0 ] 0.4;

    rhoMax          rhoMax [ 1 -3 0 0 0 ] 1.5;



   residualControl

    {

        p               1e-2;

        U               1e-4;

        e               1e-3;



        // possibly check turbulence fields

        "(k|epsilon|omega)" 1e-3;

    }                       // residual control temporarily not used

}



PIMPLE

{

    momentumPredictor yes;

    nOuterCorrectors  1;

    nCorrectors       1;

    nNonOrthogonalCorrectors 0;

    rhoMin            rhoMin [ 1 -3 0 0 0 ] 0.5;

    rhoMax            rhoMax [ 1 -3 0 0 0 ] 2.0;



    maxCo             0.2;

    rDeltaTSmoothingCoeff 0.1;

    rDeltaTDampingCoeff 1;

    maxDeltaT         1;

}



relaxationFactors

{

    fields

    {

        p               0.03;

        rho             0.05;

    }

    equations

    {

        U               0.07;

        "(k|epsilon|omega)"   0.04;

        e               0.05;

        h               0.01;

    }

}





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

Quote:

Originally Posted by adarsh tiwari (Post 484831)

Hi all,
relaxationFactors
{
fields
{
p 0.03;
rho 0.05;
}
equations
{
U 0.07;
"(k|epsilon|omega)" 0.04;
e 0.05;
h 0.01;
}
}

// ************************************************** *********************** //[/CODE]

Is it a serious issue (bug)?

A user can edit those files.

Use the following conditions for relaxation factors:

relaxationFactors
{
fields
{
p 0.3;
rho 1;
}
equations
{
U 0.7;
"(k|epsilon|omega)" 0.7;
e 0.7;
h 0.7;
}
}

User has an option to edit the "fvSchemes" as well depending on problem statement.

Best Luck!

Quote:

Originally Posted by makaveli_lcf (Post 331828)

Hi!

Code:

gradSchemes

{

    default         cellLimited leastSquares 1;

}



divSchemes

{

    default        none;

    div(phi,epsilon) Gauss linearUpwind grad(epsilon);  // OF20x syntax

    div(phi,k)       Gauss linearUpwind grad(k);  // OF20x syntax

    div(phi,U)       Gauss linearUpwind grad(U);  // OF20x syntax

    div((nuEff*dev(T(grad(U)))))     Gauss linear;  // OF20x syntax

}

My example which I use with pimpleFoam.

It has been a while since this thread is posted, can anyone please answer my question?

In this case, does it mean that divergence scheme Gauss linearUpwind uses the gradient scheme of respective variables?

Thanks,
Sunil.

Quote:

Originally Posted by sunilkonatham (Post 702084)

Yes, you are right. It can either use specific scheme listed in the gradient section or just use default scheme. You can also specify your name for the scheme to use it with several variables, for example like this:

Code:

gradSchemes

{

   default      none;

   grad(DDD)    cellLimited Gauss linear 1;

   grad(p)      leastSquares;

}



divSchemes

{

    default        none;

    div(phi,epsilon) Gauss linearUpwind grad(DDD);

    div(phi,k)       Gauss linearUpwind grad(DDD);

    div(phi,U)       Gauss linearUpwind grad(DDD);

}

Great. Thanks a lot Dr. Vakhrushev.