Playing with phase separation in a lattice-Boltzmann fluid simulator I wrote recently. Lattice-Boltzmann sims are very easy to write, and if you ever wanted to write a fluid sim, but find the math daunting, they're a good place to get started. They have other virtues (and limitations) beyond ease of implementation. For instance, it's very easy to simulate multiple phases and immiscible fluids with an LB sim.
For the second two pictures, I tweaked the sim so that the fluid flow favours the x- and y-axis directions.