Thermal convection in granular gases with dissipative lateral walls

TL;DR

This paper demonstrates that dissipative lateral walls induce a unique form of thermal convection in granular gases, distinct from buoyancy-driven convection, confirmed through experiments and molecular dynamics simulations.

Contribution

It reveals a new convection mechanism caused by dissipative lateral walls in granular gases, differing from traditional buoyancy-driven convection.

Findings

Dissipative lateral walls induce a distinct thermal convection in granular gases.

Convection cells form next to each wall and shrink with increased gravity or grain number.

Simulations confirm experimental observations and show convection diminishes at high gravity or grain count.

Abstract

We consider a granular gas under the action of gravity, fluidized by a vibrating base. We show that a horizontal temperature gradient, here induced by limiting dissipative lateral walls (DLW), leads always to a granular thermal convection (DLW-TC) that is essentially different from ordinary buoyancy-driven convection (BD-TC). In an experiment where BD-TC is inhibited, by reducing gravity with an inclined plane, we always observe a DLW-TC cell next to each lateral wall. Such a cell squeezes towards the nearest wall as the gravity and/or the number of grains increase. Molecular dynamics simulations reproduce the experimental results and indicate that at large gravity or number of grains the DLW-TC is barely detectable.