Water flow simulator?

[bigmac]

Is there such a thing? I'm planning out a new tank and know which pumps I'd like to use and I have a theory in my head as to how many return lines I'm using and where the bulkheads will be placed. My return pumps are adjustable flow as well. It would be great if there was a software program that I could plug all the information into and it would simulate the expected flow within the tank (and show any dead areas). Am I just dreaming at this point; or does something like this exist?