[nicoletta90]

Hi everybody,
I'm new in this forum, and I'm not really able with UDF.
In my case study, I have 2 inlets and I need to define 4 UDF (2 for velocity, 2 for epslon).
I know that I can interpret only one UDF, so I write them in one file, but the software interpret only the first two.

Attached the UDF file (note that until now I used them without problems, and that the software don't give me any message error).

# include "udf.h"

DEFINE_PROFILE(inlet_velocity_first, thread, index)
{
real p[ND_ND];
real y, u0=3.56, yref=10.0;
face_t f;
begin_f_loop (f, thread)
{
F_CENTROID (p,f,thread);
y=p[1];
F_PROFILE(f,thread,index)=-u0*pow(y/yref,0.14);
}
end_f_loop(f, thread)
}


# include "udf.h"

DEFINE_PROFILE(inlet_epson_first, thread, index)
{
real p[ND_ND];
real y, y0=0.03, u0=0.257;
face_t f;
begin_f_loop (f, thread)
{
F_CENTROID (p,f,thread);
y=p[1];
F_PROFILE(f,thread,index)=(1/0.42)*pow(u0,3.0)/(y+y0);
}
end_f_loop(f, thread)
}​


# include "udf.h"

DEFINE_PROFILE(inlet_velocity_second, thread, index)
{
real p[ND_ND];
real y, u0=1.47, yref=10.0;
face_t f;
begin_f_loop (f, thread)
{
F_CENTROID (p,f,thread);
y=p[1];
F_PROFILE(f,thread,index)=u0*pow(y/yref,0.14);
}
end_f_loop(f, thread)
}


# include "udf.h"

DEFINE_PROFILE(inlet_epson_second, thread, index)
{
real p[ND_ND];
real y, y0=0.03, u0=0.106;
face_t f;
begin_f_loop (f, thread)
{
F_CENTROID (p,f,thread);
y=p[1];
F_PROFILE(f,thread,index)=(1/0.42)*pow(u0,3.0)/(y+y0);
}
end_f_loop(f, thread)
}​

Thanks a lot!

[blackmask]

There are some non-printing characters after the last "}" in the second and fourth DEFINE_PROFILE macro, and one of them is the NULL character. Please delete any thing from the last "}" line of the second macro and the #include line of the third macro, and retype the "}". You only need to include "udf.h" once.

[nicoletta90]

Now it works, thanks a lot for your help!

[Oula]

Dear nicoletta90 and blackmask

I also want to write a UDF of transient mass flow rate for inlet boundary. I want to inject a gas with flow rate of 1.5 Cubic meter per hour, i.e. same flow rate to be injected every one hour of the physical flow-time. Do you have any experience with this? do you think the code below might fit the case?

#include "udf.h“

DEFINE_PROFILE(transient_mf, thread, position)
{
face_t f ;

real t = RP_Get_Real("flow-time"); /* to calculate the physical time step*/

begin_f_loop(f, thread)
{
if (t==0,3600, 2*3600, 3*3600, 4*3600, 5*3600)
{
F_PROFILE(f, thread, position) = 53;
}
else
{
F_PROFILE(f, thread, position) = 0;
}
}
end_f_loop(f, thread)
}