[Ahmed kandil]

Dear ,
udf code.jpg
i need to write UDF code for changing inlet temp depending on inlet temp .

[pakk]

Homework for which course?

[AlexanderZ]

you may find the example to start with in anays fluent customization manual
look for DEFINE_ON_DEMAND

[Ahmed kandil]

I don’t understand what you mean ..

[pakk]

1. Open the manual.
2. Look for DEFINE_ON_DEMAND
3. Read, and find out how close this example is to your problem.
4. Try to make the necessary changes, test your resulting UDF.
5. If it does not work like you want, show what you tried and what the outcome was.

[Ahmed kandil]

I do it to calculate inlet temp based on outlet temperature but there are a large divergence has occurred so what is the problem ?
i need from this code inlet and outlet temp for 252000 second.
the first assumption for inlet temp=288.15k and this temp will reduced as fluid pass through borhole and the outlet temp used again to calculate inlet temp from heating equation and still working to decrease error and give accurate outlet and inlet temp.
noted that ID=17 is outlet temp.

#include "udf.h"

#define Q 5600
#define m 0.248
#define Cp 4200
#define stop_time 252000

real ave_T;

DEFINE_ADJUST(temp_ave, domain)
{
int ID = 17;
int i=0;

real total_temp = 0;
real T;

Thread *thread = Lookup_Thread(domain, ID);
face_t face;

begin_f_loop(face, thread)
{
T = F_T(face, thread);
total_temp = total_temp + T;
i = i + 1;
}
end_f_loop(face, thread)

ave_T = total_temp / i ;

printf("outlet average of temp : %f\n" , ave_T);
}

DEFINE_PROFILE(Temp_inlet,t,i)
{
face_t f;

real current_time;
current_time=CURRENT_TIME;

if (current_time < stop_time)
{
begin_f_loop(f,t)
{
F_PROFILE(f,t,i)= (Q/(m*Cp)) + ave_T;
}
end_f_loop(f,t)
}
else
{
begin_f_loop(f,t)
{
F_PROFILE(f,t,i)= 288.15;
}
end_f_loop(f,t)
}
}
this the error[erature using GMRES to enhance linear solver robustness.

Divergence detected in AMG solver: temperature
turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 56612 cells
outlet average of temp : -nan(ind)

Divergence detected in AMG solver: temperatureoutlet average of temp : -nan(ind)

Divergence detected in AMG solver: temperatureoutlet average of temp : 5000.000000

Divergence detected in AMG solver: temperatureoutlet average of temp : -nan(ind)

Divergence detected in AMG solver: temperatureoutlet average of temp : -nan(ind)

Divergence detected in AMG solver: temperatureoutlet average of temp : -nan(ind)

Divergence detected in AMG solver: temperature
Error at host: floating point exception
Error at Node 0: floating point exception
Error at Node 1: floating point exception
Error at Node 2: floating point exception
Error at Node 3: floating point exception
Error at Node 4: floating point exception
Error at Node 5: floating point exception
Error at Node 6: floating point exception

===============Message from the Cortex Process================================

Compute processes interrupted. Processing can be resumed.

================================================== ============================

Error: floating point exception
Error Object: #f
Registering Udf, ("F:\Eng.Ahmed Kandiel\UDF.c")

Calculation complete.]