Learning Forum

[Silversea]

Hi, 

Thanks for the reply.

This is the code I tested:

======================================================================

/*

Calculate the average velocity at outlet and print it.

*/

 

#include "udf.h"

 

DEFINE_EXECUTE_AT_END(pre_time)

{

Domain *d;

Thread *t, *t_f;

cell_t c;

face_t f;

real V, sum = 0., sum_V = 0.;

real ave;

int zone_ID = 7; // outlet ID

 

d = Get_Domain(1);

 

t_f = Lookup_Thread(d,zone_ID);

begin_f_loop(f,t_f)

{

t = THREAD_T0(t_f); // get cell thread

c = F_C0(f,t_f); // get corresponding cell

V = C_VOLUME(c,t);

sum_V += V;

sum += V*C_U_M2(c,t);

}

end_f_loop(f,t_f) 

 

ave = PRF_GRSUM1(sum/sum_V);

 

if I_AM_NODE_ZERO_P

{

Message("ave = %g\n",ave);

}

}

======================================================================

 

It is a simple code that calculates and prints the average velocity at a boundary. I used it on both 2D and 3D models (very simple models such as 2D laminar flow in a pipe).

First, I run the model for a few time steps, e.g. time steps =10. Then I apply the UDF, and continue the simulation.

 

When I change the line "sum += V*C_U_M2(c,t);" to  "sum += V*C_U_M1(c,t);" or "sum += V*C_U(c,t);" it perfectly works without error and prints the average velocity. But with C_U_M2(c,t) (or any other _M2 macros) it encounters the segmentation error.