Hello everybody,

I have a big pool fire 25*16.5 m2 in a domain of 125*100*50. (fuel kerosene, heat release 670 MW) When looking at the soot mass fraction profiles I see that i dont have a value of 0 except at the wind inlet 1 m distance. The fire is located at the distance of 50 m from the wind inlet. Even in the far away regions I have a mass fraction of 4e-4 and as I said practically no regions with 0 soot mass fraction.

What do you think about this?

Hi,

Isn't a mass fraction of 4e-4 close enough to zero? If you want to get closer to zero, try converging tighter and/or using double precision numerics.

Glenn Horrocks

Hi Glenn,

thank you for your suggestion.The domain is large, so i would expect that the soot mass fraction to be 0 in the far field, no??

Indeed the soot mass fraction and the nuclei are harder to converge. I am doing a transinet simulation and i can get tight convergence on each timestep for the rest of variables, but the soot hmm it is more difficult.

Is there a way to speed the convergence for the soot?

I read on other forum that there are some problems with the Soot model in CFX.

In my case the simyulation crash when adding the soot. I have tried 2 cases:

1)to runn it with the option Fuel consumtion reaction on- in this case the simulation crashed : fatal overflow in linear solver 2) to runn it without this option and in this case I think the results are not accurate

Does anyone has a solution for this problem???