Jul 27, 2012 at 8:44 PM
Edited Jul 28, 2012 at 9:33 AM
What's basic about fluid dynamics even if it's just water? :)
Farseer 2 had some water-related stuff that was pretty cool. The only thing that remains now is the buoyancy controller but older code could be ported in theory with good knowledge of the engine.
JBox2D has a simple SPH-ish implementation (recently ported to Box2D) - LiquidDemo. Performance is... what it is.
There are some great open source implementations of SPH fluids around like FLUIDS v2. It runs on the GPU.
It will be extremely difficult to obtain two-way interactions with the rigid body solver, though. Recently there was an attempt to integrate FLUIDS in Bullet. Only one way interaction is available at the moment - i.e. rigid bodies can serve as boundary conditions.
PhysX has fluids with two-way interaction. It doesn't work on mobile and probably won't any time soon. Fluids are very computationally expensive.
Fluids can also be faked by using a lot of small spheres (particles) with zero friction. This could work in some simple scenarios combined with appropriate rendering tricks and as a bonus no changes to the engine are needed. Performance will depend on the number
of particles. Something like that:
[EDIT] One of the few games having fluids and using Box2D with some explanation and lots of tricks