Rob Milburn

Numerical Simulations of Liquid-Immersed Vibrated Granular Beds.

Abstract: We describe a numerical simulation of a sinusoidally agitated granular bed immersed in a liquid. The granular particles are modelled by soft-sphere potentials and the fluid flow through the bed is treated at the coarse-grain level in the incompressible limit. Under vibration, fluid is driven through the bed, causing granular convective motion which results in tilting of the upper surface. This symmetry-broken state is stable, resulting from a balance of constructive and destructive motions occurring during each vibratory cycle. The simulations allow us to investigate both the granular motion and the fluid motion involved in tilting. Our simulations compare well with high-speed camera observations of granular and fluid tracer motion for systems immersed in water.
The results from a granular system immersed in an incompressible fluid have relevance to Faraday piling in air, where there is still debate over the detailed mechanism for the phenomenon.