[mengyue1]

Hi guys, i am confused about my work now.
the question is: water falls down along a vertical heated tube (falling water film) to cool the tube, meanwhile, air is forced into the tube from the bottom of the tube to enhance the evaporative effect of the falling water film.
i use VOF model to track the interface of gas phase and liquid face, as for evaporation, i found udf in some website, but it just involves water and steam, so how i write udf to introduce the mass of vapor to the air, i mean, in my case, there are two kinds of gas in the gas phase, how i treat them using VOF? or maybe VOF dosen't work for this case？
thanks a lot!
Regards!