MyPhysicsLab – Fluid Dynamics
Here are some simulations of fluid dynamics in shallow water with different initial conditions. The quantity represented by color is the vorticity, which is the amount of "swirl" at a given point. The range of colors is from blue through green and yellow to red.
A paper on how these simulations were constructed is available here
in Adobe PDF format.
The movies are in the Microsoft .avi format, and so are likely only playable on Windows machines.