[randomPhil]

hi,

I am currently trying to write udf to time-average some LES flow properties that Fluent doesn't time-average as default.

As a starting point I have copied an execute_at_end udf from the manual, exactly as it is written in the manual, yet I get error messages when I try to compile or interpret it.

My udf is as follows:
#include "udf.h"

DEFINE_EXECUTE_AT_END(averager)
{

Domain *d;
Thread *t;
/* Integrate dissipation. */
real sum_diss=0.;
cell_t c;
d = Get_Domain(1); /* mixture domain if multiphase */

thread_loop_c(t,d)
{
begin_c_loop )c,t)
sum_diss += C_D(c,t) * C_VOLUME(c,t);
end_c_loop(c,t)
}
}

printf("Volume integral of turbulent dissipation: %g\n", sum_diss);
fflush(stdout);
}

And the error message I get is:
line 15: begin_c_loop: undeclared variable

Does anyone have any ideas?

Thanks

[Hershey]

It looks like your parentheses are backwards in your cell loop. Try this:

#include "udf.h"

DEFINE_EXECUTE_AT_END(averager)
{

Domain *d;
Thread *t;
/* Integrate dissipation. */
real sum_diss=0.;
cell_t c;
d = Get_Domain(1); /* mixture domain if multiphase */

thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
sum_diss += C_D(c,t) * C_VOLUME(c,t);
}
end_c_loop(c,t)
}
}

printf("Volume integral of turbulent dissipation: %g\n", sum_diss);
fflush(stdout);
}

[Hershey]

Actually, after looking at this UDF, you have an extra } after the end_c_loop(c,t). Remove it to make sure all brackets are balanced. After doing that, the UDF compiled on my system without error.