Walks in Rigid Environments: Continuous Limits
We derive the continuous limits of kinetic equations for spatially discrete systems generated by the motion of a particle in a random array of scatterers. The type of scatterer at a vertex changes after the r-th visit of the particle to this vertex, where 1≤r≤∞. Such deterministic cellular automata belong to the class of walks in rigid environments. It has been recently shown that they form the simplest dynamical models with sub-diffusive, diffusive and super-diffusive behaviour. Due to the deterministic character of the dynamics, the continuous limit equations obtained for these models are of the Euler type rather than the diffusive type. The reason for that is that the fluctuations in these models are relatively small and there is no scaling of probabilities similar, for example, to those in the case of biased random walk, that can account for them.