how to write C routines for this problem.
 

hello everyone. i want to write UDF for multiphase flow with these conditions as below. please find the attachment to hav a detail view of my problem. can any one help me please.

Two phase flow

"The effective thermal conductivity, keff,
is calculated as the average of thermal conductivities of the liquid
and vapor phases, weighted by their respective volume fractions.
The gradients of temperature and volume fraction are calculated
using divergence theory, and are used to determine the three
source terms given by Eqs as shown in the attachment. The source terms are evaluated
throughout the computational domain. However, their value
is evaluated to equal zero everywhere, except in the vicinity of
the liquid–vapor interface where the gradient of volume fraction
is non-zero.