Best OSS CFD Package For High School Physics?

RobHart writes "I am teaching a 'physics of flight' unit to grade 11 Physics students. Part of the unit will have the students running tests on several aerofoils in a wind tunnel. I also want to expose them to a Computational Fluid Dynamics package which will allow them to contrast experimental results with those produced by the CFD package. There are a number of open source CFDs available (Windows- or Linux-based are both fine), but I don't have much time to evaluate which are the simplest to use in terms of setting up the mesh, initial conditions, etc. — a very important issue as students do not have much time in this unit." Can anyone offer insight about ease of use for programs in this niche?