RF looked 'relatively' understandable, at least the basics but I haven't looked at it since I think version 3, years ago. I found a link to the very basics of fluid sim in Blender.

http://ci-blender.deviantart.com/art/Blender-Fluid-Sim-Basics-27479896 

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken