Solidworks 2010 has what's called floXpress. It anylizes the flow of fluid or air. I'm not sure if its what you would need or not as I really haven't used it much, but the capabilities are there. Also, Im not sure if older versions of Solidworks would have it.

You could probably do a google search and look up the floxpress and get some video demo's to see if whats your after though.