Dense Granular Poiseuille Flow

We consider a dense granular shear flow in a two-dimensional system. Granular systems (composed of a large number of macroscopic particles) are far from equilibrium due to inelastic collisions between particles: an external driving is needed to maintain the motion of particles. Theoretical description of driven granular media is especially challenging for dense granular flows. This paper focuses on a gravity-driven dense granular Poiseuille flow in a channel. A special focus here is on the intriguing phenomenon of fluid-solid coexistence: a solid plug in the center of the system, surrounded by fluid layers. To find and analyze various flow regimes, a multi-scale approach is taken. On macro scale, granular hydrodynamics is employed. On micro scale, event-driven molecular dynamics simulations are performed. The entire phase diagram of parameters is explored, in order to determine which flow regime occurs in various regions in the parameter space