Ahh, see, that is an SPH particle-based fluid solver. Blender currently has one of these and it’s quite fast already. The only issue is that we don’t have a way of skinning the particles at the moment. SPH solver wouldn’t be too hard to get working on the GPU. An actual fluid simulation, like the one in Blender currently, is a completely different beast, and there’s a reason it’s just now being added to Realflow. GPUs only really calculate well when you can run many concurrent, similar processes at the same time, and grid-based fluid solvers don’t fit so well into this criteria.