[ZengJiChuan]

The speed changes periodically with time, and UDF is loaded by means of compilation. Fluent is parallel computing, and there are other UDFs. But the recorded data shows that the speed has not changed over time. Please help to see what might be the reason. The following is UDF:
#include"udf.h"
DEFINE_PROFILE(air_inlet_velocity,thread,position)
{
real t,v,a;
face_t f;
begin_f_loop(f,thread)
{
t=RP_Get_Real("flow-time");
{
a=(int)t%240;
if(a>=0&&a<60)
{
v=(float)a/60+4.63;
}
else if(a>=60&&a<180)
{
v=-(float)a/60+6.63;
}
else if(a>=180&&a<240)
{
v=(float)a/60+0.63;
}
}
F_PROFILE(f,thread,position)=v;
}
end_f_loop(f,thread)
}

[Diconico]

Could it be because you are running in parallel? Maybe, because your domain is solved by diferent nodes, and you are looping in the domain, it is overwriting something, try running in serial, just to see if the velocity changes. When I have more time, I'll give a better look to give you a proper answer.

[ZengJiChuan]

Originally Posted by Diconico

Could it be because you are running in parallel? Maybe, because your domain is solved by diferent nodes, and you are looping in the domain, it is overwriting something, try running in serial, just to see if the velocity changes. When I have more time, I'll give a better look to give you a proper answer.

Thank you for your answer. I have found my wrong place. I shouldn't use cast, which causes a to be zero at the beginning.