[aleisia]

1.

begin_f_loop(f,t)
if PRINCIPAL_FACE_P(f,t) /* tests if the face is the principle face FOR COMPILED UDFs ONLY */
{
NV_D(flux, =, F_U(f,t), F_V(f,t), F_W(f,t)); /* defining flux in terms of velocity field */
NV_S(flux, *=, F_R(f,t)); /* multiplying density to get flux vector */
F_AREA(A,f,t); /* face normal vector returned from F_AREA */
massflowrate += F_YI(f,t,i)*NV_DOT(flux,A); /* dot product of the inlet surface flux and area vector, multiplied by the mass fraction of species i */
}
end_f_loop(f,t)

2.
if PRINCIPAL_FACE_P(f,t) /* tests if the face is the principle face FOR COMPILED UDFs ONLY */
{
massflowrate += F_YI(f,t,i)*F_FLUX(f,t); /* dot product of the inlet surface flux and area vector, multiplied by the mass fraction of species i */
}

I guess I don't need the begin_f_loop and end_f_loop, right?
but how am I supposed to do with "massflowrate += F_YI(f,t,i)*NV_DOT(flux,A); "?
or "massflowrate += F_YI(f,t,i)*F_FLUX(f,t);"


thanks