[vekh]

Hello guys!
I need to write UDF that will return x and y (and z for 3D) coordinates of place where there is fractional quantity of phase (black box region at the picture).
As I'm quite new to the all multiphase things I've used code from this forum. After few changes it's look like:

#include "udf.h"

DEFINE_SOURCE(source,c,t,dS,eqn)
{
real source, alpha, xc[ND_ND];
Thread *mixture_thread;
Thread **pt;
Domain *domain; 
int zoneid = 2;
domain = Get_Domain(1);
mixture_thread = Lookup_Thread(domain,zoneid);
pt = THREAD_SUB_THREADS(mixture_thread);

alpha = C_VOF(c,pt[1]);
Message("cell volume fraction = %f \n xc = %f \n yc = %f \n",alpha, xc[0], xc[1]);
source =2;
dS[eqn] = 0;
return source;
}

Sadly, the messages in Fluent console returns only:

cell volume fraction = 0.000000
xc = 0.000000
yc = 0.000000
cell volume fraction = 1.000000
xc = 0.000000
yc = 0.000000

few times.
My fluid zone ID taken from GUI is 2. I have two phases:

• argon phase (ID 2)
• air phase (ID 3)

Could someone give me some hint?