CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   Choice of species in prePDF (http://www.cfd-online.com/Forums/fluent/27727-choice-species-prepdf.html)

Elias Castro June 14, 2000 05:47

Choice of species in prePDF
 
I'm trying to model a combustion system of kerosene (C12H23) with prePDF using the equilibrium chemistry approach.

My problem is that I follow the guidelines on choosing species of the user's manual, and one of them says "For hydrocarbon combustion systems, it is recommended that you include C(S) and H_2O(L)."

I find a big difference depending on whether I include C(s) or not. When I include it, I get a high value for the mass fraction of C(s) in the rich limit (0.4 !), but I don't get lighter hydrocarbons (apart from CH4).

If I remove C(s) from the list, I get a much more "interesting" description of the system, with formation of CH4, C5H6, C2H4, C2H6, etc.

Here is the problem: my lack of knowledge about this processes. My questions are:

a) Do you think that the mass fraction of C(s) I get is too high?

b) Is my second choice really more "interesting" ? or is it better to get an equivalent description of the system with a smaller number of species? ; and in that case, how can I test that equivalence?

Thanks a lot,


Graham Goldin June 15, 2000 17:03

Re: Choice of species in prePDF
 
I do not include C(s) in the species list; there is usually not enough time in a flame for solid C to equilibrate.


All times are GMT -4. The time now is 12:33.