When I use star_cd for simulation of the flow fields in a room with fire, the resultant temperature is always much higher than the experimental data. I use CH4 as fuel and use the pdf combustion model. Can anyone with the experience working on fire simulation give me some comments? I would highly appreciate the help.

Ko

Did you include thermal radiation or not?

no. i didn't include the radiation effect. Does it influence so much? Thanks for reply.

Ko

For high temperatures, the T^4 scale of heat transfer through radiaton is quite significant. However, it should not affect your results much if BOTH the walls of your test rig and CFD model are adiabatic.

Try comparing with your combustion products from measurement. The PPDF model is not the most accurate model for combustion around and may have given you a more complete combustion than is realistic. Try refining cell sizes to get a more accurate mixing of hot/cold, product/reactant-rich streams in your model.