Fluid-induced particle-size segregation in sheared granular assemblies

Abstract

We perform a two-dimensional molecular-dynamics study of a model for bidisperse granular systems under conditions of simple shear flow. We find that if the ratio of shear rate to viscosity is small, then the particles in the system arrange themselves in bands of big and small particles oriented along the direction of the flow. Each band contains particles of one species only. We present a mechanism for this particle-size segregation phenomenon based on the observation that segregation occurs if the viscous length scale introduced by a liquid in the system is smaller than the mean free path of the particles. For large values of shear rate to viscosity the system remains disordered. \textcopyright{} 1996 The American Physical Society.