UDF to monitor minimum pressure on the wall

Arvind Jayaprakash

Hello World!

Can any of you help me debug the UDF appended below. I am trying to identify the minimum pressure on the wall at the end of each time step. It is a 2D flow over a airfoil problem.

Thanks.

/************************************************** *********************************************** -----USER DEFINED FUNCTION HOOKS Fluent V6.3---------------------

UDF to identify the lowest pressure on the wall at the end of each time step ************************************************** ************************************************/

#include "udf.h" #include "stdio.h" #include "mem.h " #include "threads.h"

DEFINE_EXECUTE_AT_END(vapor) {

real pmin =0.;

real pre;

real flow_time = RP_Get_Real("flow-time");

int ID = 7; /* Enter the zone ID of Wall from the Boundary Conditions Panel*/

/* Get the domain using Fluent utility */

Domain *d;

d = Get_Domain(1);

/* Get the thread ID */

Thread *t = Lookup_Thread(d, ID);

face_t f;

if (BOUNDARY_FACE_THREAD_P(t)) /* Check the for boundary face thread */

{

FILE *fp = NULL;

char filename[ ]="wall-minimum-pressure.txt";

fp = fopen(filename, "w");

/* Loop over all faces in the wall face-thread */

begin_f_loop(f, t)

{

pre = F_P(f,t); /* get face pressure */

if (pre < pmin) pmin = pre; /* Compute minimum face pressure */

}

end_f_loop(f,t)

Message("\nWriting the lowest pressure on the wall to %s...",filename);

fprintf(fp,"%g %f \n",pmin,flow_time);

fclose(fp);

}

else

{

Error("Please enter the correct Zone ID from the Boundary Conditions Panel");

}

}