[tilek]

Dear all,

I was trying to write a udf that calculates the gradient of the temperature field using "Green-Gauss Cell-Based Gradient Evaluation" of each cell as in below. Even if the code compiles with no error, I get segmentation error just before it evaluates the line "c0 = F_C0(f,t);". Can someone give me insights where I went wrong. My approach used nested loop (calling c_face_loop(c,t,i) while inside begin_c_loop (c,t)). Also, I know the gradient of a scalar, eg. C_T_G, is accessible if needed to be used - but I didn't want to use that - as the idea was to get myself an in-depth insight into Fluent udf writing. Thankyou.

/************************************************** *********************/
/* UDF for computing gradT using "Green-Gauss Cell-Based Gradient Evaluation" of each cell.
==> structured mesh */
/************************************************** *********************/
#include "udf.h"
#include "sg.h"
#include "flow.h"
#include "mem.h"
#include "metric.h"
DEFINE_ADJUST(adjust_fcn, domain)
{
Thread *t, *t0, *t1 = NULL;
cell_t c, c0, c1 = -1;
face_t f;
int i = 0;
real area = 0.0, A[ND_ND], phi_fA[ND_ND], zro = 0.0, phi_f;
thread_loop_c (t,domain)
{
if (NULL != THREAD_STORAGE(t,SV_T) &&
NULL != T_STORAGE_R_NV(t,SV_T_G))
{
begin_c_loop (c,t)
{
i = 0;
F_AREA(A,C_FACE(c,t,i), C_FACE_THREAD(c,t,i)); /*Get the area vector*/
NV_VS(phi_fA, =, A,*,zro);
c_face_loop(c,t,i)
{
F_AREA(A,C_FACE(c,t,i), C_FACE_THREAD(c,t,i)); /*Get the area vector*/
if (BOUNDARY_FACE_THREAD_P(t)) /*Most face values will be available*/
{
/*Nothing to do since adiabatic wall assumed*/
}
else
{
c0 = F_C0(f,t);
t0 = F_C0_THREAD(f,t);
c1 = F_C1(f,t);
t1 = F_C1_THREAD(f,t);
phi_f=(C_T(c,t0)+C_T(c,t1))/2.;//eq. 20:30 tg
NV_VS(phi_fA, +=, A,*,phi_f);
}
}
C_UDSI(c,t,0) = NV_MAG(phi_fA)/C_VOLUME(c,t); //gradT
}
end_c_loop (c,t)
}
}

}