Deterministic lattice Lorentz gas. II. Mirror model

For pt.I see ibid., vol.24, p.787-806 (1991). As a model for diffusion, a lattice version of the Lorentz gas is studied, using specular collision rules. A previously developed theory, containing the molecular chaos approximation, several ring approximations and the effective medium approximation (EMA), is applied and compared with simulations. The correction to the Boltzmann equation result, resulting from effective medium approximation (EMA) is opposite to the simulation results. This indicates that other diagrams than ring diagrams should be considered, which is peculiar if one considers the successes of the EMA for other models. This is investigated by using variants of the model. The diffusion tensor is in general nonisotropic; the corresponding features are qualitatively described by theory.