Comparison of compression vs shearing near jamming, for a simple model of athermal frictionless disks in suspension

TL;DR

This study compares how compression and shear induce jamming in a simplified model of frictionless disks, revealing similar jamming points for compression and slightly higher ones for shear, with consistent critical scaling behavior.

Contribution

It provides a detailed numerical comparison of jamming behavior under compression and shear in athermal frictionless disks, including anisotropy analysis of force networks.

Findings

Isotropic and uniaxial compression yield the same jamming packing fraction.

Shear-induced jamming occurs at a higher packing fraction.

Critical exponents are consistent across different deformation modes.

Abstract

Using a simplified model for a non-Brownian suspension, we numerically study the response of athermal, overdamped, frictionless disks in two dimensions to isotropic and uniaxial compression, as well as to pure {\color{black}and simple} shearing, all at finite constant strain rates $\dot\epsilon$. We show that isotropic and uniaxial compression result in the same jamming packing fraction $\phi_J$, while pure shear and simple shear induced jamming occurs at a slightly higher $\phi_J^*$, consistent with that found previously for simple shearing. A critical scaling analysis of pure shearing gives critical exponents consistent with those previously found for both isotropic compression and simple shearing. Using orientational order parameters for contact bond directions, we compare the anisotropy of the force and contact networks at both lowest nematic order, as well as higher $2n$-fold order.