Abstract: A multispecies,multispeeds lattice Boltzmann model is presented to study the mass diffusion properties.The diffusion equations are derived by the Chapman-Enskog method.The one dimensional simulations for the sinusoidal concentration distributions are compared with the theoretical results,showing good agreement.The numerical simulations for 2-D convection diffusion problems are also presented.

Key words: Lattice Boltzmann, mass diffusion, multi-species, multi-speeds