VOF and setting boundary conditions

dave00001

Hello all, I am somewhat new to Fluent, and I can't seem to find any answers to my questions in the user's guide, so here goes:

I am trying to model melting/solidification inside various enclosures, using the VOF model. I will have two phases, air and the PCM, and I am wondering how to set the boundary conditions. I have solidification/melting enabled, as well as the multiphase (VOF, Explicit), and I have no problem with the surface tension/contact angles.. I just have no way of defining exactly WHERE the phase interaction is.. (separate zones with porous walls?) Again I am new at this so any help would be greatly appreciated.