Shear instabilities in granular mixtures

TL;DR

This paper reports the discovery of a new shear-induced instability in granular mixtures, leading to striped segregation patterns, studied through molecular dynamics simulations and connected to pattern formation phenomena.

Contribution

It introduces a novel dynamical instability in granular media under oscillating shear, expanding understanding of segregation and pattern formation mechanisms.

Findings

Identification of a Kelvin-Helmholtz-like instability in granular mixtures

Formation of striped segregation patterns under oscillating shear

Connection between instability and granular flow pattern formation

Abstract

Dynamical instabilities in fluid mechanics are responsible of a variety of important common phenomena, such as waves on the sea surface or Taylor vorteces in Couette flow. In granular media dynamical instabilities has just begun to be discovered. Here we show by means of molecular dynamics simulation the existence of a new dynamical instability of a granular mixture under oscillating horizontal shear, which leads to the formation of a striped pattern where the components are segregated. We investigate the properties of such a Kelvin-Helmholtz like instability and show how it is connected to pattern formation in granular flow and segregation.