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-   -   turbulentHeatFluxTemperature heat capacity of what material? (https://www.cfd-online.com/Forums/openfoam-solving/134990-turbulentheatfluxtemperature-heat-capacity-what-material.html)

massive_turbulence May 7, 2014 13:22
turbulentHeatFluxTemperature heat capacity of what material?
 
Hello everyone,

Looking at the source for the turbulentHeatFluxTemperatureFvPatchScalarField class at

https://github.com/OpenFOAM/OpenFOAM...hScalarField.H

The heat capacity at constant pressure is listed

Code:
hotWall
        {
            type            turbulentHeatFluxTemperature;
            heatSource      flux;        // power [W]; flux [W/m2]
            q              uniform 10;  // heat power or flux
            alphaEff        alphaEff;    // alphaEff field name;
                                        // alphaEff in [kg/m/s]
            Cp              Cp;          // Cp field name; Cp in [J/kg/K]
            value          uniform 300; // initial temperature value
        }
If I had a box full of air with a wall made of steel transferring heat would I use the heat capacity of air or steel. I don't suppose the steel part would even matter for the simulation but I'm just not sure if it's simply the air Cp that would be needed. If it's for steel then how come there's no length requirement for the conductor (from the formula for thermal conductivity)?

thanks to anyone for clearing it up.

jherb May 20, 2014 11:19
With the turbulentHeatFluxTemperatureFvPatchScalarField boundary conditions you transfere a certain amount of heat (either defined as flux, a.k. power/area or total power for the whole surface) into the fluid. Heat conduction in the boundary is not considered, so the heat capacity is the one of the fluid. If you want to simulation also the solid and the heat conduction inside it, you have to go with the multi region solver (see the corresponding tutorias, e.g. heatTransfer/chtMultiRegionFoam etc.)

massive_turbulence May 20, 2014 16:16
Quote:
Originally Posted by jherb (Post 493141)
With the turbulentHeatFluxTemperatureFvPatchScalarField boundary conditions you transfere a certain amount of heat (either defined as flux, a.k. power/area or total power for the whole surface) into the fluid. Heat conduction in the boundary is not considered, so the heat capacity is the one of the fluid. If you want to simulation also the solid and the heat conduction inside it, you have to go with the multi region solver (see the corresponding tutorias, e.g. heatTransfer/chtMultiRegionFoam etc.)
Thank you, that's exactly what I was thinking too but I didn't know about the multi region solver.

jherb May 20, 2014 17:47
Also have a look at this boundary condition:
https://github.com/OpenFOAM/OpenFOAM...hScalarField.H
This might also apply in your case.


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