Swirling Granular Matter: From Rotation to Reptation

TL;DR

This paper investigates a new phenomenon in swirling granular matter, showing a transition from rotation to reptation at a critical packing density, supported by experimental and simulation data.

Contribution

It introduces a novel effect in granular materials under swirling motion, identifying a density-dependent transition in rotational behavior.

Findings

At low densities, granular material rotates with the container.

At high densities, the cluster exhibits reptation in the opposite direction.

Critical packing density aligns with molecular dynamics simulations.

Abstract

A novel effect in a granular material under swirling motion of the container is presented. At low packing densities the material rotates in the same direction as the swirling motion of the container (rotation). At higher densities the cluster of granular material rotates in opposite direction (reptation). The change of the direction of the motion of the cluster takes place at a critical packing density while the diffusion coefficient changes significantly. The measured critical density of the packing is in good agreement with results obtained by molecular dynamics simulation.