Journal of Statistical Physics, Vol. 66, Nos. 3/4, 1992, p. 1165-1176.
A microscopic method for the generation of invasion percolation structures using "armies" of interacting random walkers is presented. Two distinct species are used to simulate the invading and defending fluids of a fluid invasion process. Trapping of the defending species is accomplished purely by local rules, without the need to repetitively check the connection between the to be displaced" defender phase and the sink.