two phase flow, UDF

two phase flow, UDF

I have two-phase flow problem. I want to write udf to modify source term of the momentum for the secondary phase. Could you please help me how to ascess the data in the UDF? Thank you so much!

DEFINE_SOURCE(mom_source,c,t,dS,eqn) { real x[ND_ND]; real source;

source = c_u(c,t); ? for secondary phase ? dS[eqn] =c_w(c,t); ? for secondary phase?

return source; }