[NonStopEagle]

Hello everyone,
I am having trouble running the following udf. Its giving me a segmentation fault, but as far as i know, there seems to be nothing wrong with it. I suspect the Lookup_Thread() is the problem...
Also I am running Fluent 18.1

the udf is :


#include "udf.h" /* must be at the beginning of every UDF */
#define k_B 1.3805e-23 /* Boltzman constant (j/K)*/
#define sigma 419e-12 /* molecular diameter*/
#define sigma_v 1 /* Tangential momentum accommodation coefficient*/
#define sigma_T 1 /*Thermal accommodation coefficient*/
#define pi 3.14159 /* pi number*/
#define sqrt_2 1.41421 /* sqrt(2) number */
#define len = 20e-5;

FILE* slip;

DEFINE_ON_DEMAND(wall_slip_velocity)
{
Domain* domain;
double T, P, density, MU, K, landa, a_m, du_da, dT_dx, u_f, DUY, DVY, DUX, DVX, u, v;
face_t f;
Thread* t0;
cell_t c0;
double Slip_Vel;
domain = Get_Domain(1);

t0 = Lookup_Thread(domain, 8);
slip = fopen("Slip_Velocity.out", "w");
if (slip == NULL)
{
Message("UDF cannot open file");
}
else
{
begin_f_loop(f, t0)
{
T = C_T(c0, t0); /* temperature of the cell */
P = C_P(c0, t0); /* peressure of the cell */
density = C_R(c0, t0); /* density of the cell*/
MU = C_MU_L(c0, t0); /* laminar viscosity of the cell */
u = C_U(c0, t0);
v = C_V(c0, t0);
K = C_K_L(c0, t0); /* thermal conductivity of the cell */
landa = (k_B * T) / (sqrt_2 * pi * sigma * sigma * P); /* mean free path line */
DUX = C_DUDX(c0, t0);
DVX = C_DVDX(c0, t0);
DUY = C_DUDY(c0, t0);
DVY = C_DVDY(c0, t0);
Slip_Vel = (((2 - sigma_v) / sigma_v) * landa * (((DUX + DVX) * (v / sqrt(u * u + v * v))) - ((DUY + DVY) * (u / sqrt(u * u + v * v)))));
fprintf(slip, "%f\n", Slip_Vel);
}
end_f_loop(f, t0)
}
}

I would appreciate it if someone could help me solve this problem.
Thanks in advance.


NonStopEagle

[AlexanderZ]

but as far as i know, there seems to be nothing wrong with it

how do you know, that there is no other problems except Lookup_Thread() macro?

compile your code and read log.
stop open new threads for same problems

best regards