[ponghe]

Hi everyone,

Wonder if you ran into similar problem with rhoSimpleFoam when simulating high velocity 3D duct flow.

I have an exhaust plenum with inlet velocity at 160 m/s and 490 deg C (Ma=0.2-0.3).

The geometry looks something like this:
https://www.cfd-online.com/Forums/at...1&d=1585946075

My fvSolution setup as follow:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \    /   O peration     | Version:  2.2.0                                 |
|   \  /    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-08;
        relTol          0.05;
        smoother        GaussSeidel;
//        cacheAgglomeration off;
        nCellsInCoarsestLevel 19; //sqrt(nCells)
//        agglomerator    faceAreaPair;
//        mergeLevels     1;
    }

    h
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-06;
        relTol          0.01;
    }

    "(U|k|epsilon)"
    {
        solver          smoothSolver;
        smoother        GaussSeidel;
        nSweeps         2;
        tolerance       1e-07;
        relTol          0.01;
    }
}

SIMPLE
{
    nUCorrectors    2;
    nNonOrthogonalCorrectors 0;
    pMinFactor          0.8;
    pMaxFactor          1.3;
    
    residualControl
    {
        p               1e-6;
        U               1e-5;
        h               1e-5;
	k				1e-5;
	epsilon			1e-5;
	omega			1e-5;
        
    }
}

relaxationFactors
{
    fields
    {
        p               0.5;
        rho             0.8;
    }
    equations
    {
        U               0.5;
        "(k|epsilon)"   0.5;
        h               0.5;
    }
}


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

My fvScheme is "run of the mill". I didn't bother tuning it yet.

Basically my solution never converges no matter how fine the mesh becomes. The pressure residual always oscillates substantial amounts (-1e5 to 5e5 every couple of iteration steps)

I also have tried running this case in of2.3 and of6 and found no differences.

At low flows of 40 m/s or less, my solutions converges very nicely.

Much appreciated if someone can shed some lights on this!