[soohoha]

Hello,
I want to find the coordinates of the boundary face cells adjacent to the side wall for a condensation simulation.

Since my inlet geometry is too complex, creating a film is very difficult. Therefore, I am trying to write a UDF to set the liquid volume fraction to 1 for cells located within 0.001 mm in the y-direction from the adjacent side wall.

Before implementing this, I first attempted to extract the first cell adjacent to the side wall using a connectivity macro. Then, I planned to use c_face_loop for this cell and apply if(THREAD_ID(C_FACE_THREAD(c0, t0, j)) to sort only the faces belonging to the same thread as the inlet boundary face.

However, when I run the code, only the thread corresponding to the side wall is being extracted, and not the inlet boundary face. Could you help me resolve this issue?

Here is my udf code
{
#include "udf.h"
#include "mem.h"
#include "sg_mphase.h"

const int WALLIDS[] = { 171 }; // side wall id
#define NUM_WALLIDS (sizeof(WALLIDS) / sizeof(WALLIDS[0]))
#define inlet_id 5 // inlet boundary conditions id

DEFINE_ON_DEMAND(mark_boundary_cells_all)
{
#if !RP_HOST
Domain *domain = Get_Domain(1);
Thread *t;
Thread *t0;
Thread *inlet_thread;
face_t f;
face_t face;
cell_t c0;

int i;
int j;

for (i = 0; i < NUM_WALLIDS; ++i)
{
int wall_id = WALLIDS[i];
t = Lookup_Thread(domain, wall_id);
inlet_thread = Lookup_Thread(domain, inlet_id);
Message("inlet thread %d\n", inlet_thread);

begin_f_loop(f, t)
{
c0 = F_C0(f, t);
t0 = F_C0_THREAD(f, t);
if (t0 != NULL)
{
C_UDMI(c0, t0, 0) = 1.0;
}

c_face_loop(c0, t0, j)
{
if (THREAD_ID(C_FACE_THREAD(c0, t0, j) == inlet_thread)
{
F_UDMI(c0, t0, 1) = 1.0;
/*Message("Face_thread_id = %d\n", THREAD_ID(C_FACE_THREAD(c0, t0, j));*/
}
face = C_FACE(c0, t0, j);
}
}
end_f_loop(f, t);
}
#endif
}
}