I am doing a shock tube simulation, that is, a tube with a diaphragm in the middle, on one side of the diaphragm, the presure is 1 bar, and on the other side is 5 bar. When the diaphragm suddenly brakes, a shock wave generate. The problem is: what boundray condition should I set for the diaphragm, and how can I brake it? Please give me some help, thank you.

If you do not need to know exactly how the diaphragm breaks (which could be rather difficult?), just start the patched solution (see my last tip on how to set initial conditions below) with an interior at the diaphragm boundary. Assume you started your solution zero seconds after breaking.

thank you very much, I did it. But do you konw how to generate a moive file in fluent when the shock wave goes from one side to another? Or the moive can only be generate from tecplot?

I think the easiest way is to pre-define what you want to look at, say pressures for example. Use a macro to define the sequence plot/hardcopy while solving so that you need only to save the images at e.g. every time step, and not a substantial amount of dat files.

Sorry mate, I havn't catch your idea, would you please tell me step by step that how to use macro? (Please take static pressure for example.) I am really looking forward of your answer. Thank you.

I think the manuals explain pretty well how to deal with the macro recording. If there is something in the manual that you don't understand, come again. In essence, you "record" a number of commands that should be performed every X:th iteration. Start under menu Solve - execute commands.

Regards Anders