What are some basic, open source aerodynamics or CFD simulation software that can import Blender or Sketchup models? I am looking for software that is easy-to-use, free, and suitable for educational purposes.
CFD requires a mesh of the model. To my knowledge, blender and sketchup do not do this. You may need an intermediary mesh generator to realize any cfd simulations, freeware or otherwise. Beware that mesh generators produce a plethora of different file formats which may or may not be readable in your cfd simulator of choice.
If you're looking for a good open source cfd simulator, i'd recommend OpenFOAM. Beware: it is neither simple to understand or use and i don't recommend it unless you really have a good grasp of fluid dynamics snd numerical discretization and solver methods