Wall function for DPM needed
 

Hello to all!
I want to model kerosine-air evaporating and mixing device. Kerosine liquid will be injected into swirling air flow. Mass flow rates: kerosine - 5 g/s, air - 83 g/s. Temperatures: kerosine - 300 K, air - 611 K. I read that discrete phase model is suitable for such problem (I think volume fraction of kerosine is not more than 10%, by the way, can anybody explaine me how to calculate this fraction?:)).
In this case I will have spherical liquid kerosine droplets of diameter 1 mm. The idea is that those droplets will be moved by air to the wall of the device and then evaporate on it (in case they don't evaporate before that). Temperature of the wall is also 611 K.
And now I don't know what wall function for DPM to choose. There are some of them: escape, trap, etc. But unfortunately my Fluent tutorial says nothing about it.
Please, can someone with experience in DPM or multiphase flow modeling clarify for me what wall function I need to have in order to obtain phisicaly right condition!

cheers