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-   -   Problem going from incompressible to compressible (https://www.cfd-online.com/Forums/openfoam/122822-problem-going-incompressible-compressible.html)

bgraves August 28, 2013 17:49
Problem going from incompressible to compressible
 
Hi everyone,

I am relatively new to OpenFOAM and in the past only ran simulations with the incompressible assumption. Now my research requires me to run without this assumption ie. compressible flow. I ran some simulations using simpleFoam and got good results. I am now trying to run the same simulations with rhoSimpleFoam. The simulation has zero pressure gradient and zero temperature gradient.

The first simulation is just flow over a flat plate at M=0.2 so the compressibility should only have a very small affect. However, when I run the simulations with rhoSimpleFoam I get an error that says "Maximum number of iterations has been exceeded." After looking through different forums I saw that this error is probably due to initial/boundary conditions. Since the simulation ran and produced good results running in incompressible mode, the only files that are different are for temperature, alphaT, and the thermophysicalProperties. I was wondering if anyone could look these over and make sure that I have not made some silly error.

Thanks,
-Ben

My boundary conditions for temperature and alphaT are shown below, as well as the thermophysicalProperties file
Code:
thermoType
{
    type            hePsiThermo;
    mixture        pureMixture;
    transport      sutherland;
    thermo          hConst;
    equationOfState perfectGas;
    specie          specie;
    energy          sensibleInternalEnergy;
}

mixture
{
    specie
    {
        nMoles      1;
        molWeight  28.9;
    }
    thermodynamics
    {
        Cp          1004.9;
        Hf          0;
    }
    transport
    {
        As          1.4792e-06;
        Ts          116;
    }
}
Temperature:
Code:
internalField  uniform 300;

boundaryField
{

    front
    {
        type            empty;
    }
    back
    {
        type            empty;
    }
    wall
    {
        type            zeroGradient;
    }
    symm
    {
        type            symmetryPlane;
    }
    top
    {
        type            fixedValue;
        value          $internalField;
    }
    inlet
    {
        type            fixedValue;
        value          $internalField;
    }
    outlet
    {
        type            inletOutlet;
        value          $internalField;
        inletValue      $internalField;
    }
}
alphaT:
Code:
internalField  uniform 0;

boundaryField
{
    front
    {
        type            empty;
    }
    back
    {
        type            empty;
    }
    wall
    {
        type            alphatWallFunction;
        value          uniform 0;
    }
    symm
    {
        type            symmetryPlane;

    }
    inlet
    {
        type            calculated;
        value          uniform 0;
    }
    top
    {
        type            calculated;
        value          uniform 0;
    }
    outlet
    {
        type            calculated;
        value          uniform 0;
    }
}
Thanks f

jherb September 3, 2013 08:54
I think your problem might be related to this: http://www.cfd-online.com/Forums/ope...tml#post425211

What are your U and p/p_rgh boundary conditions?

You could also try the (transient) pimple solver.


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