[rahulsuresh89]

I need help to write a UDF to vary the inlet mass flow rate (step input)..I need a step input..Is it possible? I just know the macros to be used is DEFINE_PROFILE for the boundary conditions. Please help me out with the UDF code.

[amir_yousefi]

Hi
You can see the examples of FLUENT 6.3 UDF manual about DEFINE_PROFILE. It's easy. for example, below is a code that define parabolic profile for inlet.

#include "udf.h"
DEFINE_PROFILE(Re270_art_profile,t,i)
{
real x[ND_ND]; /* this will hold the position vector */
real xcor,ycor;
face_t f;
begin_f_loop(f,t)
{
F_CENTROID(x,f,t);

xcor=x[1];
ycor = x[2];
F_PROFILE(f,t,i) = 0.13883*(1 - ((xcor)*(xcor)+(ycor)*(ycor))/(0.004*0.004));
}
end_f_loop(f,t)
}

Best