Transient periodic analysis & Boundary conditions

Michele

Hi everybody! I'm trying to manage a transient periodic analysis of a fluid moving in an Y-shaped tube. Does anybody know what are the appropriate boundary conditions to be imposed? i'm working at it using udf transient profiles of :

- velocity

- pressure

Do you know if it's possile to impose mass-outflow(is it something like defining mass-inlet at the outlet surfaces?)

thanks

Michele