[siamak1438]

Hey.
I want to simulate a geometry with two different velocity inlets. Because of the time variable velocities in both of the inlets, I have to write separate UDF for both of them. So, my question is that how can I use two unsteady velocity UDF? Or how can I allocate two different unsteady_velocity for two different faces?

[Bionico]

Hello siamak1438,
you can write two different Velocity-Profiles in 1 UDF: you have just to name them with different names and then select the correct profile in boundary condition!
For example:

DEFINE_PROFILE(unsteady_velocity1, thread, position)
{
face_t f;
real t = CURRENT_TIME;
...

DEFINE_PROFILE(unsteady_velocity2, thread, position)
{
face_t f;
real t = CURRENT_TIME;
...

Best regards

[ghost82]

Flavio is right,
I add only 2 things:
write only one line for #define "udf.h" and put all the code in one file.

Daniele

[Kokemoor]

You might be able to use profiles instead of UDFs. They're less powerful, but simpler. Check out Section 6.6 of the Fluent User's Guide.