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chtMultiRegionFoam - defining thermal properties in a solid composite

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Old   November 5, 2018, 04:41
Default chtMultiRegionFoam - defining thermal properties in a solid composite
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Adam
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Hello,

I found this forum while troubleshooting a few of my OpenFoam issues and have finally hit one that I haven't been able to resolve on my own. I am having trouble defining the thermal properties of my physical regions in OpenFoam version 5 and was hoping that someone might be able to point me in the right direction.

Problem Statement
I would like to model the transient heat transfer in a composite material comprised of cylindrical fibres in a matrix. As the fibres are perpendicular to the heat flow, this is a 2D simulation. The two materials have different heat conductivity/density/heat capacity. We assume that these properties don't vary with temperature, and for the moment, would like to assume zero thermal resistance at the interface.

Meshing and BCs
I have made the mesh using gmsh, with two physical volumes and a shared physical surface to represent the interface. The front and back planes are empty, while the top/bottom are zeroGradient and the left/right sides are at a fixed temperature.

I have defined initial and boundary (compressible::turbulentTemperatureCoupledBaffleMix ed;) conditions in the 0/ directory. When I run the follwing, everything looks normal in Paraview.
Code:
gmshToFoam
splitMeshRegions -cellZonesOnly -overwrite

My constant/regionProperties are defined as
Code:
regions
(
    fluid       ()
    solid       (matrix fibres)
);
Note: I am using OpenFoam Version 5

I am unsure of how to modify the constant\fibres\thermophysicalProperties and constant\matrix\thermophysicalProperties dictionaries. I have found solidProperties files in the src\thermophysicalModels\thermophysicalProperties\ solidProperties\ directory but I don't see how to use/modify them.

Is it possible to directly define the solid properties? Or do I need to define a thermoType based on the user guide's section on ThermoPhysical Models? If I try to run chtMultRegionFoam using the following thermoType in the thermophysicalProperties dictionary, I get an error.
Code:
thermoType
{
    type            heSolidThermo;
    mixture         pureMixture; 
    transport       constIso;
    thermo          hConst;
    equationOfState rhoConst;
    specie          specie;
    energy          sensibleEnthalpy;   
}
The error is
Quote:
--> FOAM FATAL ERROR:
cannot find file "C:/PROGRA~1/blueCFD/ofuser-of5/run/compositeFibres/0/matrix/p"
This does not make sense to me, as the only variable of interest is the temperature; pressure should not play a role.

Edit: I tried defining the pressure as a constant everywhere in 0/fibres/p and 0/matrix/p now the simulation runs with the thermophysicalProperties defined as:
Code:
thermoType
{
    type            heSolidThermo;
    mixture         pureMixture; 
    transport       constIso;
    thermo          hConst;
    equationOfState rhoConst;
    specie          specie;
    energy          sensibleEnthalpy;   
}

mixture
{
    specie
    {
        molWeight 1;
    }
        transport
    {
        kappa   80;
    }
    thermodynamics
    {
        Hf      0;
        Cp      450;
    }
    equationOfState
    {
        rho     8000;
    }
}
Is this sort of a work-around the define constant thermal properties? Or have I made some mistake that will soon come back to bite me?
SamMallinson and Yue Qiu like this.

Last edited by Adam_K; November 5, 2018 at 06:02.
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