[ophr]

I've been running solid-liquid phase change simulations of pure substances on OpenFOAM using buoyantPimpleFoam and solidificationMeltingSource. So far so good, but my main problem is making sure everything is being setup correctly, as it's been quite difficult (at least for me) to find information about the software structure.


More specifically, my works requires me to setup the properties of the material I'm working with, like its molar mass, viscosity and expansion coefficient correctly. This is done in both thermophysicalPropeties and fvOptions (where solidificationMeltingSource is configured) dictionaries. OpenFOAM is usually pretty transparent with its units, for example in the blockMeshDict and U dictionaries: Both show the units they're being setup at very clearly.

However, both thermophysicalProperties and fvOptions don't: I'm simply forced to assume that every number I type in is in SI units; except for the molar mass, in which case it given in g/mol. I've already tried searching in the official OpenFOAM documentations and on a few websites, but I couldn't find an answer. Actually, I find the official documentations (in both openfoam.com and openfoam.org) to be lacking in detail.

So, can somebody please point me where I can find information about how the values in these dictionaries are treated dimensionally? Maybe the way they're processed depends on the solver I'm using (from what I read, it seems to be that way)? Am I doing a poor job at researching, or is openfoam not that well documented in general?

As an example, here are the fvOptions and thermophysicalProperties dictionaries I'm using in an attempt to replicate Voller and Brent's [1] gallium solidification simulation. This was done in OpenFOAMv1812 from openfoam.com (OpenCFD):

thermophysicalProperties

/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  6
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      thermophysicalProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

thermoType
{
    type            heRhoThermo;
    mixture         pureMixture;
    transport       const;
    thermo          hConst;
    equationOfState rhoConst;
    specie          specie;
    energy          sensibleEnthalpy;
}



mixture
{
    specie
    {
        molWeight       697.23; // g/mol
    }
    thermodynamics
    {
        Cp              381.5; 
        Hf              0;
    }
    transport
    {
        mu            1.81e-3; 
        Pr              2.16e-2;
        kappa       32;
    }
    
    equationOfState
    {
        rho         6093;
    }
}


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

fvOptions

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  6                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvOptions;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solidificationMeltingSource1
{
    type            solidificationMeltingSource;
    active          yes;

    solidificationMeltingSourceCoeffs
    {
        selectionMode all;
        
        Tmelt           302.93;
        L               80160;
        thermoMode      thermo;
        beta            1.2e-4;
        rhoRef          6095;
        Cu                 1.6e6; // Constant C (dimensionless)
        q                   1e-3; // Constant ς (dimensionless)
    }
}

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

Thanks in advance for your patience!



[1] BRENT, A. D., VOLLER, V. R., REID, K. J., et al. “Enthalpy-porosity te- chnique for modeling convection-diffusion phase change: application to the melting of a pure metal”, Numerical Heat Transfer: An International Journal of Computation and Methodology, v. 13:3, pp. 297–318, 1988.

[Adam_K]

Have you see this thread? Maybe it can help you.

Thermophysical Property Units

[ophr]

Originally Posted by Adam_K

Have you see this thread? Maybe it can help you.

Thermophysical Property Units

Many thanks! That link was quite helpful.


Seems like the dictionary's values are given in SI units, except for molar quantities, which are standardized as kmol. That's interesting...


Furthermore, the numbers are treated as dimensionless, and there is information about the units they're given in header files on the source code. Now I know where to look to confirm any remaining doubts.