[Jackino777]

hi, I have a problem in writing a UDF for a variable temperature in a 3D cell zone.
This is my first UDF and I don't know very well the C programming, so is like impossible defining the function for me in a few days.
Do you know how can I write a linear function for temperature, where:
Z=0 m => T=24 °C
Z=-3 m => T=18 °C
also:
Z< -3 m => T=18 °C

Thank you!

[`e`]

First, convert your temperature listing to a series of equations that you'll later code into with conditional if statements; it appears there's two segments of the temperature distribution (one linear and one constant). Then have a read of the UDF manual in the section on the DEFINE_PROFILE macro where the usage is detailed and several examples are provided.

[Jackino777]

Thanks for the advices.
I tried to write the code, but I don't know how to put the two conditions (linear and constant) in a single UDF, can you help me with this?
For now I write only the linear part.

The code is:

#include "udf.h"

DEFINE_PROFILE(pressure_profile, t, i)
{
real x[ND_ND]; /* this will hold the position vector */
real z;
face_t f;

begin_f_loop(f, t)
{
F_CENTROID(x,f,t);
z = x[2];
F_PROFILE(f, t, i) = 297+2*z;
}
end_f_loop(f, t)
}

I also put an image of the result

[Jackino777]

I solved it, i've tried a lot of time and now it's ok.
I write this one, and thanks for everything:

#include "udf.h"

DEFINE_PROFILE(pressure_profile, t, i)
{
real x[ND_ND]; /* this will hold the position vector */
real z;
face_t f;

begin_f_loop(f, t)
{
F_CENTROID(x,f,t);
z = x[2];
if (z > -3)
F_PROFILE(f, t, i) = 291+2*z;
else
F_PROFILE(f, t, i) = 291;
}
end_f_loop(f, t)
}