[new_cfd]

I'm trying to write a program that linearly increases the heat flux on one side of the wall. How do I determine the number of cells in the first column of the mesh? Please do help.

[pakk]

I'm trying to write a program that linearly increases the heat flux on one side of the wall.

So go to the help, see that there is an example for a parabolic profile, and change it to linear...

#include "udf.h"
DEFINE_PROFILE(lin_incr,t,i) {
 face_t f;
 float x[ND_ND];

 begin_f_loop(f,t) {
  F_CENTROID(x,f,t);
  F_PROFILE(f,t,i) = 213.12512 + 1.135 * x[0]; 
   /* change the coefficients above to what you need */
 }
 end_loop(f,t);
}

How do I determine the number of cells in the first column of the mesh?

Why do you want to know this? It has nothing to do with your first question.

[new_cfd]

Thanks a lot.
I thought I would need it to determine the rate of increase.

[new_cfd]

Also, how do I linearly increase from 0 to 500?

[pakk]

Choose the coefficient such that it is 0 on one end and 500 on the other end.

[new_cfd]

I used the code

F_PROFILE(f,t,i) = 0+1.25*x[0]

Will the above work? I aimed to increase from 0 to 500 by increasing each cell by 1.25.

[pakk]

This will give 0 at x=0m, and 500 at x=400m.

So if you have a 400 meter long boundary, starting at x=0, then it works.

If not, do some (simple) mathematics. You (should) know at which x-position you want zero heat flux, and you (should) know at which x-position you want 500 heat flux. So you have to points, find a line that goes through these two points, write down the equation, and put this equation in your udf.

[new_cfd]

It worked for the right vertical wall. But, for my left vertical wall it did not. I used 0 + 1250 y[0].
Can you tell me what to use for the left one? One time when I tried, the heat flux continued to the bottom portion as well and didn't stop.

Also, how do I know from which cell the centroid calculation starts? From the top most cell or bottom?