Temperature errors on fire simulation?

raymond

I have tried STAR-CD to do the fire simulation for several cases. I set the fire source as a volume heat source with user subroutine sorent. The result looks fine except at the location of fir source:

THE location of MAXIMUM TEMPERATURE is not inside the fire source, but at the top of the fire source, say the ceiling just above the fire location.

I have tried the same case with CFX and Pheonix, they all present the reasonable result. But why the STAR-CD could not?

BTW, my setting is density=f(T) for ideal gas and apply MARS differencing scheme for all variables. I have also tried the SFCD scheme. There is no improvement.

Could anybody tell me what the reason of it and how to avoid such thing?

Thanks!