DrAmine
Ansys Employee

Mass transfer should use a diffusive Interfacial Area: that is what I recommend and I know that this might be discussed: several scientists have different approach on that. I recall we even pubslished a paper for condensation on droplet where we have shown that smoothing the Interfacial area will help in getting the real phyiscal area. 

Again I cannot provide an alternative for this. I just made a comment that you need to have the gradients valid to use that function. At least that function works for my small case.