[aleisia]

There is a so2-air mixture passing through a surface inlet, I want to know the SO2 mass flow rate, so I need to use F_YI(f,t,i), my question is, is this F_YI (f,t,i) the average mass fraction already, or it is something else? I know that by writing f,t, the program will automatically go through all the surfaces on the same thread to calculate the mass fraction, without using begin_f_loop, am I getting this right?

My old code is:

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)

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); "

thanks