This video was made using some examples included in the diewald_fluid library for Processing, created by Thomas Diewald:
This library allows to simulate fluids in realtime, either on the CPU or the GPU, in the latter case with GLSL shaders through the GLGraphics library. Using the GPU often results in fluid simulations running 10 to 20 times faster than the equivalent system on CPUs. The simulations in this video were generated with the GPU versions of the examples.
diewald_fluid requires the GLGraphics library installed on the computer (version 0.99 or newer):