This seems to be a version of a lattice gas fluid model. (Or, more precisely, lattice-boltzmann, since it allows for fractional values of fluid occupancy per ce

This seems to be a version of a lattice gas fluid model. (Or, more precisely, lattice-boltzmann, since it allows for fractional values of fluid occupancy per cell.) I had a Santa Fe institute monograph on this back in the day, and I seem to recall that they ended up using a hexagonal grid, in order to achieve the required isotropy of fluid behaviour. Might be something to consider.