Suppression and emergence of granular segregation under cyclic shear

TL;DR

This study investigates how cyclic shear influences granular segregation, revealing that flow reversibility and convective patterns are key to segregation onset, with implications for understanding granular flow behavior.

Contribution

It uncovers the role of flow reversibility and convection in granular segregation under cyclic shear, highlighting the transition mechanisms.

Findings

Segregation occurs with less reversible particle trajectories.

Convective flow emerges during segregation transition.

Steady shear leads to segregation, cyclic shear can suppress it.

Abstract

While convective flows are implicated in many granular segregation processes, the associated particle-scale rearrangements are not well understood. A three-dimensional bidisperse mixture segregates under steady shear, but the cyclically driven system either remains mixed or segregates slowly. Individual grain motion shows no signs of particle-scale segregation dynamics that precede bulk segregation. Instead, we find that the transition from non-segregating to segregating flow is accompanied by significantly less reversible particle trajectories, and the emergence of a convective flow field.