Compaction of granular mixtures

We propose a lattice model for studying the compaction of granular mixtures under taps. Two granular species are considered: small grains with low mobilities and T-shaped grains characterized by a larger ability to move. When those grains are mixed together, the compaction dynamics is mainly controlled by the volume fraction x of the small grains. Segregation have been found on the top layers of the pile. The grain mobilities have been studied for different values of the volume fraction x. An effective grain mobility has been defined for the mixture. This mobility is given by the linear combination of the mobility of both pure species minus a non-linear interaction term. Finally, the compaction speed depends on the fraction of the anisotropic grains.