Hi,I am learning to use UDF to model a velocity_inlet boundary condition where the velocity is dependent on the time.In the fluent help,there is a example named"unsteady flow in a tube",which is similar to my problem.But when I did as what it tells me,in compile step,the fluent said "error:sinusodial-v.c:line 1arse error".I don't know what it means and what shall I do. thank you for any help.

The UDF works as copied directly off their electronic documentation. Are you on UNIX or PC?

yea, sometimes i got that message too. but after i rewrite the function, or copy paste with other name, it's solved. just try.