[Steve-Tian]

Dear all,

I have been reading this forum for a while to find the answer of my question and failed. Now I would like to kindly ask for some help with a UDF that I am trying to write.

I know how to use the DEFINE_PROPERTY macro and other macros like this, which I don't need to write thread, cell or face loop. My problem is that writing a Define on Demand macro in order to get the parameter on the boundary or interior face and execute the macro on demand. I have facing some problems when I execute the macro, and receive the error:received a fatal signal (Segmentation fault). I refer that something is wrong on the code:thread_loop_c(t,d),but I don't know exactly. PlZ give me some help, tnk!

The UDF that I have written is shown next:
DEFINE_ADJUST(adjust,d)
{
cell_t c, c0, c1 = -1;
Thread *t, *t0, *t1 = NULL;
face_t f;
real x[ND_ND];
real NV_VEC(A);
real NV_VEC(psi_vec);
real dens = 0.0;
real sum_T_A=0.0;
real sum_A=0.0;
real flux = 0.0;
t=Lookup_Thread(d,11); /*11 is the fluid domain ID*/
thread_loop_c(t,d)
{
c0 = F_C0(f,t);
t0 = F_C0_THREAD(f,t);
F_CENTROID(x,f,t);
F_AREA(A, f, t);
if (BOUNDARY_FACE_THREAD_P(t)) /*Most face values will be available*/
{
real dens;
/* Depending on its BC, density may not be set on face thread*/
if (NNULLP(THREAD_STORAGE(t,SV_DENSITY)))
dens = F_R(f,t); /* Set dens to face value if available */
else
dens = C_R(c0,t0); /* else, set dens to cell value */
NV_D(psi_vec, =, F_U(f,t), F_V(f,t), F_W(f,t));
flux = dens*fabs(NV_DOT(psi_vec, A)); /* flux through Face */
}
}
}

[pakk]

You loop over threads t, but you forget to loop over faces f.
Currently, your program does never set any "value" for f, you only tell it that it is a face. Fluent does not know WHICH face. So it gives an error when you try to get the coordinates for that face.

[AlexanderZ]

as Pakk said change

thread_loop_c(t,d)
{

to

thread_loop_f(t, domain)
{
begin_f_loop(f,t)
{

}
end_f_loop(f, t)
}

more information in Ansys Fluent Customization Manual

best regards