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Old   April 7, 2016, 08:09
Default Transport model
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AdOo
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Hi all,

I'm facing with the eternal problem of transport model...
I said "eternal" because before posting this thread, I was looking on many older posts which has been unsolved for years now.

Like most of the older post, I was initially looking for some As and Ts coefficient, in order to run reactingFoam (without reaction) using the Sutherland model (used in the counterFlowFlame2D OpenFOAM exemple).

The thing is:
  • As I said, it is very difficult to find liable values (even just values...)
  • This Transport properties model, based on modified Euken model seems not to be very accuracy.
So concretely, how do you prepare your Transport model for your simulation ?
  • Do you manage to find the Sutherland coefficient and temperature you need for your case ?
  • Do you use the polynomial model ? (but here again, there's the question on how to find the required coefficient... I can't see the light at the end of the tunnel)
  • Do you program your own Transport model ? (I'm freaking out, you're telling me that's how you do)
  • Do you simply use the const model whithout tempting to surch any coefficient... ? (I'm sure you worth better than this one)
Thank you for your replies,
Adrien
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Old   April 7, 2016, 11:18
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According https://openfoamwiki.net/index.php/Contrib/Janaf :

" In OpenFOAM the same reader, which reads the thermodynamic data of the janaf table also contains the input data of the laminar viscosity. Therefor the Sutherland formula is used, which shows a linear increasing of the viscosity depending on the temperature. The input data is hard coded and describes the temperature dependent viscosity of pure nitrogen. In a case with nitrogen as environmental gas this could be an acceptable approximation, if there are no ionization processes. "

and

" For temperatures above 10000 K the Sutherland formula is not a good approximation anymore. The beginning ionization leads to an decreasing of the laminar viscostiy. Therefor a transport model based on polynomials should be used instead. "

The question of the ability to find the Sutherland coefficients and temperatures is then still topical for those who trust on this model.
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