Temperature Dependent Thermal Properties in LaplacianFoam

Question

I'm solving the heat equation using the finite volume method in OpenFOAM and the way it is set up right now is to average the thermal properties of the temperature field. What I want to achieve is to implement the thermal properties that correspond to the temperature of each cell/mesh. Is there a way to do that through the solver itself or in the transportProperties file.

Attached is the code I'm using. I just replaced the source term with the volumetric power that is calculated by another code.

Code:

Info<< "\nCalculating temperature distribution\n" << endl;

while (simple.loop(runTime))
{
    Info<< "Time = " << runTime.timeName() << nl << endl;

    while (simple.correctNonOrthogonal())
    {
        solve
        (
            fvm::ddt(T) - fvm::laplacian(DT, T) == volPower/(RHO * CP)
        );

    }

    #include "write.H"

    Info<< "ExecutionTime = " << runTime.elapsedCpuTime() << " s"
        << "  ClockTime = " << runTime.elapsedClockTime() << " s"
        << nl << endl;
}

Info<< "End\n" << endl;

return 0;

This is the script that reads the thermal properties from the transportProperties file.

Info<< "Reading field T\n" << endl;

volScalarField T
(
    IOobject
    (
        "T",
        runTime.timeName(),
        mesh,
        IOobject::MUST_READ,
        IOobject::AUTO_WRITE
    ),
    mesh
);


volScalarField volPower
(
    IOobject
    (
        "volPower",
        runTime.timeName(),
        mesh,
        IOobject::MUST_READ,
        IOobject::AUTO_WRITE
    ),
    mesh
);



Info<< "Reading transportProperties\n" << endl;

IOdictionary transportProperties
(
    IOobject
    (
        "transportProperties",
        runTime.constant(),
        mesh,
        IOobject::MUST_READ_IF_MODIFIED,
        IOobject::NO_WRITE
    )
);


Info<< "Reading diffusivity DT\n" << endl;

dimensionedScalar DT
(
    transportProperties.lookup("DT")
);

Info<< "Reading density RHO\n" << endl;

dimensionedScalar RHO
(
    transportProperties.lookup("RHO")
);

Info<< "Reading thermal conductivity CP\n" << endl;

dimensionedScalar CP
(
    transportProperties.lookup("CP")

This is how the transportProperties file is structured

DT              DT  [0 2 -1 0 0 0 0] 1.7620248e-5; // Diffusion Coefficent 

RHO             RHO [1 -3 0 0 0 0 0] 1.52082743e3;  // Density 

CP              CP  [0 2 -2 -1 0 0 0] 707.36193;  // Heat Capacity

I want DT and CP to be dependant on the temperature of each cell.

Your Cp, DT are constant values. How they are dependent on the temperature at each cell? — s.ouchene, Jan 05 '22 at 06:12

score 0 · Answer 1 · answered Jan 11 '22 at 09:05

If you start from a newer version of laplacianFoam you will see how they have handled this for diffusivity:

Info<< "Reading diffusivity DT\n" << endl;

volScalarField DT
(
    IOobject
    (
        "DT",
        runTime.timeName(),
        mesh,
        IOobject::READ_IF_PRESENT,
        IOobject::AUTO_WRITE
    ),
    mesh,
    dimensionedScalar(dimViscosity, Zero)
);

if (!DT.headerOk())
{
    IOdictionary transportProperties
    (
        IOobject
        (
            "transportProperties",
            runTime.constant(),
            mesh,
            IOobject::MUST_READ_IF_MODIFIED,
            IOobject::NO_WRITE
        )
    );
    DT = dimensionedScalar("DT", dimViscosity, transportProperties);
}

With this, the diffusivity (DT) is now a volumetric field, but can also be initialized using a uniform constant value from the transportProperties lookup.

You would need something similar for your other property fields. Of course, you still need to implement some type of material properties, but I guess that is what you already know how to do.

Temperature Dependent Thermal Properties in LaplacianFoam

1 Answers1