Complex Flow of Granular Material in a Rotating Cylinder

TL;DR

This study uses 2D molecular dynamics simulations to analyze granular flow in a rotating cylinder, revealing irregular, avalanche-like movement, unstable convection cells, and agreement with recent experimental findings.

Contribution

It introduces detailed simulation of granular flow with spherical and nonspherical grains, highlighting irregular flow patterns and convection cells at low angular velocities.

Findings

Flow varies irregularly with time at low angular velocities

Particles exhibit stick-slip avalanches at the surface

Unstable convection cells are observed

Abstract

The flow of granular material in a rotating cylinder was simulated by molecular dynamics in two dimensions using spherical as well as nonspherical grains. At very low but constant angular velocity we found that the flow varies irregularly with time. The particles move stick-slip like i.e. there are avalanches of different size at the surface of the granular material. Observing the traces of the particles we found that there are unstable convection cells. Our results agree with recent experiments by Rajchenbach [1] and Rolf [2].