Free CFD package

You might try this site....

http://www.cfd-online.com/Links/soft.html

I don't know about a Windows version, but there is a program called OpenFOAM.

http://www.openfoam.com/

If it is available for Windoze, fine - you will be well on your way.

If not, you can download an excellent scientific Linux-based Operating System + scientific apps (including OpenFOAM), called CAELinux. I have it installed on a separate hard drive and can boot to it or Windows at startup. I'm still getting to know the system and so far it's great!

To run this, you must have a 64-bit hardware system. _{(I built my own 64-bit computer for under $450; it was about 1.5 years ago. Now it would probably be cheaper)}

cwarner7_11 knows a lot about this stuff. He'll probably show up with some more specific information.

Hope this helps