See rockmov.mpeg , a simulation peformed by graduate student John Olson in Dan Rothman's research group at MIT. The movie shows immiscible two-phase flow in Fontainebleau sandstone. The rock measures about (1mm)^2 x 2mm, or about 6 grains in the long dimension. Nonwetting fluid is injected at the left and wetting fluid is drained at the right. The simulations were performed with a 3D lattice-gas cellular-automaton model of immiscible fluids created by John Olson.
See Dan's phase separation movie. This mpeg version is slightly distorted (horizontal exaggeration).
If you are sitting at the X server from which you fired up netscape or xmosaic, try Dan's vplot movie. It allows stepping forward and back. Type "f" for faster. If there is lots of memory on your X server, the second time thru the movie should be much faster than the first.
If you have xtpen at your site, and correct mailcaps and mime.type this button should also run vplot.