I want to use pressure of 1 face in udf that compiled on other face
 

dear guys

in my udf, I need to use pressure on the face that this face isnt exist in my udf.

for example, i wrote udf and compiled on "Shadow boundary" but i need to use pressure on "Canopy Boundary" at this udf. (i need pressure difference on 2 faces)

please help to write this udf.

Hi I don't know if you already solve this problem but here is my solution (I haven't tried so you would have to play around it ok?)

-- to be inserted in your macro that has access to "Shadow Boundary" --
real FC[2];
face_t f_canopy;
int ID = 1; /* Zone ID for "Canopy boundary" this number you can find it Define> Boundary Conditions */
Thread *t_canopy = Lookup_Thread(domain, ID);

begin_f_loop(f_canopy, t_canopy) /* loop through "Canopy boundary" */
{
F_CENTROID(FC,f,thread);
printf("x-coord = %f y-coord = %f", FC[0], FC[1]);
}
end_f_loop(f,thread)

thank you,
your opinion is correct,
but i found a new way for solving my problem, i have been use THREAD_SHADOW because i want the pressure on shadow.:D

ts=TREAD_SHADOW(tf);

hi iman

i need you, my name is Redha, you can contact me on cheredha@gmail.com

i need you iman