Transverse Instability of Avalanches in Granular Flows down Incline

TL;DR

This paper models granular avalanches on inclined planes using a partial fluidization approach, revealing soliton-like structures that become transversely unstable at high inclinations, leading to fingering patterns.

Contribution

It introduces a soliton-based model for avalanches that explains transverse instability and fingering phenomena observed experimentally.

Findings

Identification of soliton-like avalanche solutions

Transverse instability occurs at high inclination angles

Instability leads to fingering and coarsening patterns

Abstract

Avalanche experiments on an erodible substrate are treated in the framework of ``partial fluidization'' model of dense granular flows. The model identifies a family of propagating soliton-like avalanches with shape and velocity controlled by the inclination angle and the depth of substrate. At high inclination angles the solitons display a transverse instability, followed by coarsening and fingering similar to recent experimental observation. A primary cause for the transverse instability is directly related to the dependence of soliton velocity on the granular mass trapped in the avalanche.