Friction-induced Shear thickening: a microscopic perspective

TL;DR

This paper presents a microscopic model explaining shear thickening in dense suspensions, highlighting the role of frictional forces and particle rotations, supported by simulations showing increased contact and energy dissipation.

Contribution

It introduces a microscopic perspective emphasizing frictional forces and rotational dynamics as key to shear thickening, supported by simulation results.

Findings

Shear thickening correlates with increased contact number and frictional energy dissipation.

Liquid-like gear-states coexist with solid-like regions at high densities.

Frustrated loops stabilize solid-like regions, increasing viscosity.

Abstract

We develop a microscopic picture of shear thickening in dense suspensions which emphasizes the role of frictional forces, coupling rotational and translational degrees of freedom. Simulations with contact forces and viscous drag only, reveal pronounced shear thickening with a simultaneous increase in contact number and energy dissipation by frictional forces. At high densities, when the translational motion is severely constrained, we observe liquid-like gear-states with pronounced relative rotations of the particles coexisting with solid-like regions which rotate as a whole. The latter are stabilised by frustrated loops which become more numerous and persistent with increasing pressure, giving rise to an increasing lengthscale of this mosaique-like structure and a corresponding increase in viscosity.