[macfly]

Hi,

Here is a simple UDF that calculates and prints the volume integral of temperature at the end of each time step:

#include "udf.h"
DEFINE_EXECUTE_AT_END(execute_at_end)
{
Domain *d;
Thread *t;
real sum_T=0.;
cell_t c;
d = Get_Domain(1);
thread_loop_c(t,d)
	begin_c_loop(c,t)
		sum_T += C_T(c,t) * C_VOLUME(c,t);  /* Integrate temperature */
	end_c_loop(c,t)
printf("Volume integral of temperature = %g K*m^3\n", sum_T);
}

Now, I would like to do a similar operation but on a boundary, with the use of the Lookup_Thread function. The UDF manual only has an example for the calculation of something in a domain (Get_Domain), not on a boundary (Lookup_Thread). I tried to modify my code with no success. I can make it work with DEFINE_ADJUST at each iteration, but it's not what I want: I want to perform some calculation on a boundary at each time step, not at each iteration.

Any idea how I can tell DEFINE_EXECUTE_AT_END to loop on a boundary?