Question about Oscillating Flow in a Tube
 

All,

I am currently trying to model oscillating flow in a long tube. At the inlet I am simulating a pressure inlet with a UDF that specifies the pressure oscillation as a function of time. I am also specifying the outlet as a pressure outlet. I have simulated this for a pressure outlet that matches the inlet and with a steady pressure. When I run the model, I do not get the correct velocity profile; at 3/4 cycle the flow should reverse but this does not happen. I am hoping that somebody can help to address what I may be doing wrong. Is a pressure outlet the right boundary? Any help on this matter would be greatly appreciated. Thanks in advance.

Ryan