Thermal convection in fluidized granular systems

Thermal convection is observed in molecular dynamic simulations of a fluidi zed granular system of nearly elastic hard disks moving under gravity, insi de a square box. Boundaries introduce no shearing or rime dependence, but t he energy injection comes from a slip (shear-free) thermalizing base. The t op wall is perfectly elastic and lateral boundaries are either elastic or p eriodic. The spontaneous temperature gradient appearing in the system due t o the inelastic collisions, combined with gravity, produces a buoyancy forc e that, when dissipation is large enough, triggers convection.