Stochastic dynamics of a sheared granular medium

TL;DR

This paper experimentally studies the intermittent stick-slip behavior of a sheared granular medium, revealing statistical regularities and proposing a stochastic model that connects granular dynamics with magnetic domain wall motion.

Contribution

It introduces a simple stochastic model for granular shear dynamics that captures experimental fluctuations and links to models used in magnetic Barkhausen noise studies.

Findings

Torque distribution shows stability properties similar to Gaussian variables but with correlations and skewness.

The stochastic model accurately reproduces the experimental intermittent behavior.

Connections are suggested between granular shear dynamics and magnetic domain wall motion phenomena.

Abstract

We experimentally investigate the response of a sheared granular medium in a Couette geometry. The apparatus exhibits the expected stick-slip motion and we probe it in the very intermittent regime resulting from low driving. Statistical analysis of the dynamic fluctuations reveals notable regularities. We observe a possible stability property for the torque distribution, reminiscent of the stability of Gaussian independent variables. In this case, however, the variables are correlated and the distribution is skewed. Moreover, the whole dynamical intermittent regime can be described with a simple stochastic model, finding good quantitative agreement with the experimental data. Interestingly, a similar model has been previously introduced in the study of magnetic domain wall motion, a source of Barkhausen noise. Our study suggests interesting connections between different complex phenomena and reveals some unexpected features that remain to be explained.