[vivek1441]

Dear community,

I am trying to 3D model a hybrid cooling system based on a liquid-cooled plate consisting of phase change material (PCM). The cold plate has one cooling channel surrounded by PCM. On passing between the PCM domain, the cooling channel divides the PCM region into two domains. A heat flux condition exits on one of the large faces of the cold plate.

I want to write a UDF to control the inlet coolant velocity so that it activates the coolant flow by 0.2m/s only when the average temperature of the PCM domain reaches above 305K, and the flow stops as soon as the average temperature decreases below 305K.


Here is the UDF:


#include "udf.h"


real calculate_average_temp(Domain *domain, int domain_id) {
Thread *t = Lookup_Thread(domain, domain_id);
cell_t c;
real total_temp = 0.0;
int total_cells = 0;


begin_c_loop(c, t) {
total_temp += C_T(c, t);
total_cells++;
} end_c_loop(c, t)

if (total_cells > 0) {
return total_temp / total_cells;
}
}



DEFINE_EXECUTE_AT_END(control_coolant_flow) {
Domain *domain = Get_Domain(58); // Use the correct fluid domain ID if different
Thread *inlet_thread;
face_t f;
real avg_temp1, avg_temp2, overall_avg_temp;


int pcm_domain_id1 = 55; // first PCM domain ID
int pcm_domain_id2 = 56; // second PCM domain ID
int inlet_thread_id = 88; // coolant inlet thread ID


avg_temp1 = calculate_average_temp(domain, pcm_domain_id1);
avg_temp2 = calculate_average_temp(domain, pcm_domain_id2);


overall_avg_temp = (avg_temp1 + avg_temp2) / 2.0;

inlet_thread = Lookup_Thread(domain, inlet_thread_id);


if (overall_avg_temp >= 305.5) {
begin_f_loop(f, inlet_thread) {
F_PROFILE(f, inlet_thread, 0) = 0.2;
} end_f_loop(f, inlet_thread)
} else {
begin_f_loop(f, inlet_thread) {
F_PROFILE(f, inlet_thread, 0) = 0.0;
} end_f_loop(f, inlet_thread)
}
}



As soon as I load the UDF and initialize it, I get a segmentation fault error and fluent crashes. Please suggest how to eliminate the problem.