Smoothing of sandpile surfaces after intermittent and continuous avalanches: three models in search of an experiment

TL;DR

This paper introduces three models to analyze how sandpile surfaces become smoother due to avalanches, distinguishing between intermittent and continuous flow regimes, aiming to guide experimental validation.

Contribution

It develops and analyzes three coupled continuum models capturing surface smoothing mechanisms in sandpiles for different avalanche flow regimes.

Findings

Models predict increased surface smoothness with avalanche activity

Different smoothing behaviors are identified for intermittent vs. continuous avalanches

Framework sets stage for experimental testing of surface dynamics

Abstract

We present and analyse in this paper three models of coupled continuum equations all united by a common theme: the intuitive notion that sandpile surfaces are left smoother by the propagation of avalanches across them. Two of these concern smoothing at the `bare' interface, appropriate to intermittent avalanche flow, while one of them models smoothing at the effective surface defined by a cloud of flowing grains across the `bare' interface, which is appropriate to the regime where avalanches flow continuously across the sandpile.