Flow from a balloon
 

I would like to hear if anyone has experience calculating the flow from something like a balloon. The problem is how to create a pressure inside a closed box and then afterwards let the fluid out of the box because a part of a wall is opened. Do you know how to start the calculations, which boundary conditions to use I would be very grateful. If you have experience solving this kind of problems in CFX4, it would be even better.

Lotte