Transitions in the Horizontal Transport of Vertically Vibrated Granular Layers

TL;DR

This study investigates how granular particles move horizontally in a vertically vibrated system with a sawtooth base, revealing complex behaviors like current reversal and phase-transition-like onset influenced by layer number and frequency.

Contribution

It combines experimental and simulation approaches to uncover novel collective behaviors and current reversals in vibrated granular layers with detailed simulation methodology.

Findings

Current can reverse as a function of layer thickness.

Transport onset occurs gradually, similar to a phase transition.

Simulations reproduce experimental results and show frequency-dependent current reversal.

Abstract

Motivated by recent advances in the investigation of fluctuation-driven ratchets and flows in excited granular media, we have carried out experimental and simulational studies to explore the horizontal transport of granular particles in a vertically vibrated system whose base has a sawtooth-shaped profile. The resulting material flow exhibits novel collective behavior, both as a function of the number of layers of particles and the driving frequency; in particular, under certain conditions, increasing the layer thickness leads to a reversal of the current, while the onset of transport as a function of frequency occurs gradually in a manner reminiscent of a phase transition. Our experimental findings are interpreted here with the help of extensive, event driven Molecular Dynamics simulations. In addition to reproducing the experimental results, the simulations revealed that the current may be reversed as a function of the driving frequency as well. We also give details about the simulations so that similar numerical studies can be carried out in a more straightforward manner in the future.