[fuad]

I am trying to modify the $FOAM_TUTORIAL/compressible/rhoCentralFoam/forwardStep of OF-2106. Then I only changed the values of velocity, pressure, temperature, and thermophysical properties to S.I. units. While this tutorial uses normalized gas. Changed the velocity, temperature, pressure from unity to 930 m/s, 873 K and 1.35e7 Pa respectively. The constant/thermoPhysicalProperties file looks like this.

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2106                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      thermophysicalProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

thermoType
{
    type            hePsiThermo;
    mixture         pureMixture;
    transport       polynomial; 
    thermo          hPolynomial; 
    equationOfState PengRobinsonGas; 
    specie          specie;
    energy          sensibleEnthalpy;

// Note: these are the properties for a "normalised" inviscid gas
//       for which the speed of sound is 1 m/s at a temperature of 1K
//       and gamma = 7/5
mixture
{
    specie
    {
        molWeight       18; 
    }
   
    thermodynamics
    {
       CpCoeffs<8>     ( 3.91269e4 -1.17335e2 1.2620e-1 4.556e-5 0 0 0 0 ); //
       Hf		3.59431e06;
       Sf		6735.18;
    }
    transport
    {
       muCoeffs<8>     ( 1000 -0.05 0.003 0 0 0 0 0 ); //
       kappaCoeffs<8>  ( -1.3719e-5 7.136029e-8 -2.4915e-11 5.6244e-15 0 0 0 0 ); //
    }

    equationOfState
    {
        Tc        647.27; // critical temp (K)
        Vc        0.056; // critical volume (m^3/kmol)
        Pc        22.12e6; //critical pressure (Pa)
        omega     0.343; // acentric factor (-) 

    }
}


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

This causes either the simulation to diverge or to maximum number of iteration error.
Is this problem related to unit of the parameters? I've checked other tutorials for rhoCentralFoam and they use S.I. unit. I am not sure what causes this issue. I tried a lot of solutions provided in this forum but none of them worked.
Here is a log file attached for convenience.

[Leckie]

What I can say about this, based on the OpenFoam documentation, is that rhoCentralFoam is already working with Mach Number reference; therefore the initial velocity parameter "3" is referring to Mach Number 3.


In this case, if you're using 980, it is not 980m/s but Mach Number 980.