Mass source term definition in UDF for an axisymmetric problem
 

Hello,

I am working on an axisymmetric domain and have to define a mass source on one of the boundaries. (It is a rectangular domain that I am using: cylinder in axisymmetric case)
The part of the UDF that computes the mass source term is as follows:

c_face_loop(c,t,i)
{
f = C_FACE(c,t,i);
tf = C_FACE_THREAD(c,t,i);

if(THREAD_ID(C_FACE_THREAD(c,t,i)) == inlet_mass_source)
{
F_AREA(A,f,tf);
area_face = A[2];
source=dens*velocity*(fabs(area_face))/C_VOLUME(c,t);
dS[eqn] = 0;
}
}

The current code results in no convergence of the x-velocity and y-velocity.
I wanted to know what area does the F_AREA calculate for an axisymmetric problem?
Also if anyone has worked on an axisymmetric problem with mass source defined, it would be of great help if they can share their procedure for defining the mass source?