[nasergasembagloo]

Dear friends,

I am trying to write a UDF to control my heating source surface boundary condition in a dish washer; it is a multi-phase problem and this UDF should check all cells to see if it contains water; if it is the UDF should get its temp and add it to a variable with the name of "temp"; also it should count the cell numbers if they contain water and add it to the "count" variable. After this it should divide "temp" variable by "count" variable to get the average temperature of all cells which contains water and write it to "twater" variable. Finally it should check if this average temperature is less or more than 338. If it is less than 338 it should set the boundary heat flux to 60000 and if its is higher than 338 it should set this "source" to zero.
I have written the following code; but I get errors continuously. Also I need to use it in parallel processing which as I read somewhere requires some corrections in code. Please help me to correct and run the code. I appreciate your help in advance.

#include "udf.h"

DEFINE_PROFILE(wallheatfluxprofile,thread,i)
{
{
Thread *t;
real temp = 0;
real count = 0;
real twater;
cell_t c;
d = Get_Domain(2);
thread_loop_c(t,d)
{
begin_c_loop(c,t)
temp += C_T(c,t);
count = count + 1;
end_c_loop(c,t)
}
twater = temp/count;
printf("temp is: %g\n", twater);
}
real source;
face_t f;
if (twater > 338)
source = 0;
else
source = 60000;

begin_f_loop(f,thread)
F_PROFILE(f,thread,i) = source;
end_f_loop(f,thread)

}

Regards,

[pakk]

Originally Posted by nasergasembagloo

Dear friends,

I am trying to write a UDF to control my heating source surface boundary condition in a dish washer; it is a multi-phase problem and this UDF should check all cells to see if it contains water; if it is the UDF should get its temp and add it to a variable with the name of "temp"; also it should count the cell numbers if they contain water and add it to the "count" variable. After this it should divide "temp" variable by "count" variable to get the average temperature of all cells which contains water and write it to "twater" variable. Finally it should check if this average temperature is less or more than 338. If it is less than 338 it should set the boundary heat flux to 60000 and if its is higher than 338 it should set this "source" to zero.
I have written the following code; but I get errors continuously. Also I need to use it in parallel processing which as I read somewhere requires some corrections in code. Please help me to correct and run the code. I appreciate your help in advance.

#include "udf.h"

DEFINE_PROFILE(wallheatfluxprofile,thread,i)
{
{
Thread *t;
real temp = 0;
real count = 0;
real twater;
cell_t c;
d = Get_Domain(2);
thread_loop_c(t,d)
{
begin_c_loop(c,t)
temp += C_T(c,t);
count = count + 1;
end_c_loop(c,t)
}
twater = temp/count;
printf("temp is: %g\n", twater);
}
real source;
face_t f;
if (twater > 338)
source = 0;
else
source = 60000;

begin_f_loop(f,thread)
F_PROFILE(f,thread,i) = source;
end_f_loop(f,thread)

}

Regards,

I don't understand what you are trying to do with the {}s... In the code below I just moved all declaration of variables to the top, and made de {}s logical. Is this what you want?

#include "udf.h"

DEFINE_PROFILE(wallheatfluxprofile,thread,i)
{
Thread *t;
real temp = 0;
real count = 0;
real twater;
cell_t c;
d = Get_Domain(2);
real source;
face_t f;

thread_loop_c(t,d)
{
  begin_c_loop(c,t)
  temp += C_T(c,t);
  count = count + 1;
}
end_c_loop(c,t);
twater = temp/count;
printf("temp is: %g\n", twater);
if (twater > 338) 	source = 0; else source = 60000;
	
  begin_f_loop(f,thread) {
    F_PROFILE(f,thread,i) = source;
  }
  end_f_loop(f,thread);
  
}

By the way: your method of taking the average cell temperature is only giving what normal people would call "averaged temperature" if the cells all have the same volume.

[nasergasembagloo]

Thank you very mcuh for your response; as I mentioned before I need to get the average temperature of water which is not included in all cells and as a result of tempreature increment reduces gradually. So what should I do to get the average temperature of water?

Regards,

[pakk]

If you want the volume-averaged temperature, the code should look something like this:

real sumtemp = 0;
real sumvolume = 0;
real twater;
cell_t c;

d = Get_Domain(2);

/* loop through all cells that contain water */
 {
  sumtemp += C_T(c,t) * C_VOLUME(c,t);
  sumvolume += C_VOLUME(c,t);
 }
end_c_loop(c,t)
twater = sumtemp /sumvolume;

But I have to say that I don't understand how you intend to loop through all cells that contain water. I don't see any line in your code at all that tries to check if the cell contains water.

[nasergasembagloo]

Originally Posted by pakk

If you want the volume-averaged temperature, the code should look something like this:

real sumtemp = 0;
real sumvolume = 0;
real twater;
cell_t c;

d = Get_Domain(2);

/* loop through all cells that contain water */
 {
  sumtemp += C_T(c,t) * C_VOLUME(c,t);
  sumvolume += C_VOLUME(c,t);
 }
end_c_loop(c,t)
twater = sumtemp /sumvolume;

But I have to say that I don't understand how you intend to loop through all cells that contain water. I don't see any line in your code at all that tries to check if the cell contains water.

Thank you very much for your answer and help; I am very new in writing UDF's. So I could do some errors in code. How can I do this? (Checking if it is water or not?)
Does your written code do this?

Best regards,