Vicente Garzó (University of Extremadura, Spain)

Enskog kinetic theory for granular mixtures. some application

Since a real granular system is usually characterized by some degree of polydispersity in density and size, flows of granular mixtures are prevalent in both nature and industry. Examples of the former include landslides, avalanches, and even planetary rings. Examples of the latter include pneumatic conveying of grains, ores, and chemicals; high- velocity fluidized beds; and mixing of pharmaceutial powders and poultry feedstock. A nonuniform particle distribution may be a property of the material itself, or it may be intentionally used to improve process performance. Perhaps most importantly, due to differences in size and/or mass of particles of each component, polydisperse mixtures exhibit particle segregation or demixing. This process, which has no monodisperse counterpart and is frequently observed in nature and experiments, cannot be explained by using the continuum models developed for systems constituted by mechanically identical particles. Consequently, it will be necessary to expand on the previous efforts made for deriving granular hydrodynamics to include multicomponent granular mixtures. The goal of this talk is to give an overview of some advances made for binary granular fluids by using the Enskog kinetic equation. Some of the results will cover aspects such as energy nonequipartition, Navier-Stokes transport properties, segregation or mixing and instabilities in freely cooling states. In some cases, the analytical results will be compared with Monte Carlo and molecular dynamics simulations, showing the reliability of kinetic theory to describe granular flows even for strong collisional dissipation.