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-   -   Tmax in reactingFoam depends on CFL-number (?) (http://www.cfd-online.com/Forums/openfoam-solving/89705-tmax-reactingfoam-depends-cfl-number.html)

andras June 20, 2011 13:55

Tmax in reactingFoam depends on CFL-number (?)
 
Dear Foamers,
I am using OpenFoam-1.7.1 (git: 03e7e056c215). There is a tight dependence between "T gas max" and the CFL number in the reactingFoam tutorial case. Lower Courant-numbers lead to lower maximum temperatures and vice versa.

In "applications/solvers/combustion/reactingFoam/chemistry.H" the line

// Chalmers PaSR model
kappa = (runTime.deltaT() + tc)/(runTime.deltaT() + tc + tk);

with an _absolute_ runTime.deltaT() clearly is an error, isn't it?

Also to test mesh dependence i tried this:

I refined the original mesh from the tutorial from 4000 -> 400000 cells (x10 in both directions) and ran the tutorial again. It crashes both in single and parallel at around 0.0007s. I also tried removing runTime.deltaT() from the kappa-equation in the source code, recompiled it, and ran it to the same effect. At some point epsilon becomes negative and the solver crashes.

Any ideas?


Cheers,
Andras


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