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r08n October 26, 2010 06:46

Temperature-dependent properties and mass conservation in porousExplicitSourceReactin
Hi *,

I modified the 'porousExplicitSourceReactingParcelFoam' to include heat sources in the energy equation and set up a very simple simulation: a box filled with pure N2, no mass flows (U=uniform(0,0,0)) and a uniform field of the heat source, in order to raise the temperature; that's just for testing purposes -- the setup will get more complex in the future. The solver uses
the polynomial coefficients defined in constant/thermo.incompressiblePoly for temperature-dependent parameters: density, heat capacity @p=const and some other. As the temperature rises, the density gets lower, therefore, the total mass in the box (calculated as m=sum_over_cells(rho(cell)*V(cell))) diminishes, but the pressure stays constant. Of course, this setup is incorrect -- it must use heat capacity @ constant volume, not @ constant pressure, and assume the compressible fluid (gas in this case). I have a few questions:
1) Is it possible to obtain somewhere the polynomial coefficients for heat capacity at constant volume? Where are the data in thermo.incompressiblePoly taken from? I couldn't find any references -- ChemKin, maybe?
2) Why does the pressure stay constant in the current simulation? Isn't 'porousExplicitSourceReactingParcelFoam' meant to be compressible solver?

The modified energy equation looks like this:
fvm::ddt(rho, h) + mvConvection->fvmDiv(phi, h)
- fvm::laplacian(turbulence->alphaEff(), h)
pWork() + parcels.Sh() + radiation->Sh(thermo) + Q_heat

All the terms on the RHS are zero, except for Q_heat, which is defined as a volScalarField with constant power density (in W/m^3).
Did I overlook something? Thank you for any pointers, hints, keywords for searching...

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