evaporation and condensation in the VOF model
 

Hi, I did a search in this forum and I saw that this subject appears in some places, so maybe someone could help me. My model includes evaporation and condensation along with free surface problem, so I need to use the VOF model. I understand that in order to this I need to include a UDF with the mass transfer equation and also to insert a heat source to the energy equation. I have a problem to find an equation that will fit this purpose. I will appreciate if someone could help me in finding one, or a UDF that include one.

Thank in advance.