one-fliud formulation twophase flow with phase cha
 

I want to know the one-fluid formulation of two phase flow with phase change, that is, the N-S euquation and energy equation. I have two problems 1. Is the energy total the same as the one without phase change? 2. How to model/interpret the source term of continuity equation?

reference:Son. Numerical Heat transfer B, 39:509-523,2001

Thanks a lot.