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April 14, 2010, 15:58 |
FireFoam what is HRR ?
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#1 |
Member
Francois Gallard
Join Date: Mar 2010
Location: Toulouse, France
Posts: 44
Rep Power: 16 |
Hi OpenFoamers,
Does anybody knows what the volumic scalar field HRR is? Because I thought that it was the combustion source term in the energy equation but it is sometimes negative. Is it divided by the cell volume, because it can raise values around+/- 1E6 ? Many thanks Francois Gallard |
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April 16, 2010, 11:37 |
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#2 |
Member
Francois Gallard
Join Date: Mar 2010
Location: Toulouse, France
Posts: 44
Rep Power: 16 |
Hi, I found this in the fireFoam source code :
HRR= - fvc::ddt(rho, hc) - fvc::div(phi, hc) + fvc::laplacian(turbulence->alphaEff(), hc); So it seems that the HRR is defined as all the source terms in the enthalpy equation except for the heat Fourier and turbulent diffusions. So, if I am right, source terms left are : - heat due to chemistery - heat due to friction, certainly close to zero because of very low Mach number of the flow - radiated heat, but I swiched the radiation off - inter spieces diffusion term, zero because all heat capacities are supposed to be equals -the pressure term, very low So I still don't understand why the heat release rate can be negative and positive depending on the cells, with so huge variations : -1E6 ; +1E6 Has anybody an idea ? |
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