Numerical simulation of mixing and segregation of granular material

Mixing and segregation of granular material, consisting of spherical particles of various sizes, stirred by a periodically moving bar was simulated numerically, using the discrete element method. It was shown that smaller particles of the granulated material tend to sink to the bottom while the larger particles rise to the top. The segregation process depends on mixing, which is more intense for higher values of the dynamic friction coefficient of the particle material. This dependence is similar to the case of hydrodynamics where mixing is more intense in more viscous fluids, but more thorough understanding of this dependence for the case of granular matter requires further investigations