Effect of microscopic inhomogeneity of the medium on reaction-diffusion front velocity

A model of random walks on an inhomogeneous lattice is used to analyze the effect of microscopic inhomogeneity of the medium on reaction-diffusion front velocity. It is shown that the front velocity can be substantially higher on an inhomogeneous lattice as compared to that on a homogeneous one with the same onsite waiting time. The increase in velocity is due to a bias in the particle distribution between sites of different types toward those with shorter waiting times. The amount of bias depends on the rate of chemical reaction: the higher the rate, the stronger the bias. The front velocity also strongly depends on the reaction mechanism, more precisely, on how product particles are distributed between sites of different types.