[ahmed425]

Dear all,

I would like to create a UDF for suction velocity on a wall. and I can't use a velocity inlet on that wall since it is an interface between two domains. There are two walls next to each other with zero thicknesses ( a wall and its shadow). I want to have suction velocity on both of these walls.

So, I was thinking about the DEFINE_ADJUST function. Can it be used for such a purpose? because based on the fluent manual it says:

DEFINE_ADJUST is a general-purpose macro that can be used to adjust or modify ANSYS Fluent variables that are not passed as arguments. For example, you can useDEFINE_ADJUST to modify flow variables (for example, velocities, pressure) and compute integrals.


but I'm having troubles in the commands of accessing the y velocity components on that wall for the fluid. This is what I came up with for now.

#include "udf.h"

DEFINE_ADJUST(myFunction,domain)
{
int zoneID;
Thread *tf;
face_t f1;

zoneID = 9.0;  // The ID of the wall on the BC list in fluent

tf = Lookup_Thread(domain,zoneID);

begin_f_loop(f1, tf)
{

THREAD_VAR(tf).fluid.velocity[1] = 0.01;

}
end_f_loop(f1, tf)


}

is the use of "THREAD_VAR(tf).fluid.velocity[1]" correct to access the y component of the velocity on the wall ? or should I use "THREAD_VAR(tf).wall.v"

The function compiles with no issues and I hooked the function using the function hooks and the simulation completes with no problems. However I can't see any difference in the results and when I plot the y component of the velocity on the wall I get a flat line of zero values.

any suggestions are welcomed.

Thank you for your help