i m using solidworks 2009 with sp3 i know its not free , but u have internet and for the people who won t spend 10000$ there are some funny sites.
as far as i know there are no good free cad softwares out there.
there is also a very good fluid simulation plugin for solidworks.
there is also a very very good free 3d scan programm.
http://www.david-laserscanner.com/
its so damn easy and we re using it for scaning small objects and parts @ home , after scanning u have to import it with solid et voilą u can du what u want with the 3d object.