[hitzhwan]

How to write a udf code that can have the below function: define a heat flux, it is 0 when the mass flow of outlet (one boundary ) is zero, and is 1000 w/m^2 when the mass flow of outlet (one boundary ) is over zero?

[AlexanderZ]

to make it works you need:
1. Define mass-flow rate as global variable
2. Find mass-flow rate value in boundary you are wanted by thread ID

int zone_ID = 2;
Thread *thread_name = Lookup_Thread(domain,zone_ID);

3. You may organize it in DEFINE_ADJUST macro to get mass-flow rate before each timestep (or iteration if steady state)
4. Set heat-flux value using DEFINE_PROFILE macro

for more details check Ansys Fluent Customization manual

[hitzhwan]

Originally Posted by AlexanderZ

to make it works you need:
1. Define mass-flow rate as global variable
2. Find mass-flow rate value in boundary you are wanted by thread ID

int zone_ID = 2;
Thread *thread_name = Lookup_Thread(domain,zone_ID);

3. You may organize it in DEFINE_ADJUST macro to get mass-flow rate before each timestep (or iteration if steady state)
4. Set heat-flux value using DEFINE_PROFILE macro

for more details check Ansys Fluent Customization manual

Because I am not familar with udf， would you please share me the code for me ，thank you so much.

[AlexanderZ]

show your code and we will try to fix it if necessary

[hitzhwan]

Originally Posted by AlexanderZ

show your code and we will try to fix it if necessary

I am familar with Profile macro，but I do not know how to use get_adjust macro, could you help me revise it , thank you so much.

#include "udf.h"

DEFINE_ADJUST(my_adjust,d)
{
Thread *t;
/* Integrate dissipation. */
real flow time;
cell_t c;

thread_loop_c(t,d)
{
begin_c_loop(c,t)
flow time= C_D(c,t)*
C_VOLUME(c,t);
end_c_loop(c,t)
}

printf("Volume integral of turbulent dissipation: %g\n", sum_diss);
}

#include "udf.h"



DEFINE_PROFILE(hf_change,thread,position)
{
face_t f;
real time,heat_flux1,heat_flux2;
heat_flux1 = 10;
heat_flux2 = 100;
time=CURRENT_TIME;
begin_f_loop(f,thread)
{

if (time<flow time)
{
F_PROFILE(f,thread,position)=heat_flux1;
}

else if (time>=flow time)
{
F_PROFILE(f,thread,position)=heat_flux2;
}

}
end_f_loop(f,thread)
}