Jamming Mechanisms and Density Dependence in a Kinetically-Constrained Model

TL;DR

This paper investigates how relaxation mechanisms like temperature and driving influence jamming and unjamming in a kinetically-constrained model, revealing the dominant role of density in dynamic heterogeneity.

Contribution

It introduces relaxation mechanisms into a spiral model to study unjamming processes at various densities, temperatures, and driving conditions.

Findings

Relaxation time of the persistence function is numerically calculated.

Spatial heterogeneity depends strongly on density, less on temperature and driving.

Three distinct relaxation mechanisms are identified for unjamming.

Abstract

We add relaxation mechanisms that mimic the effect of temperature and non-equilibrium driving to the recently-proposed spiral model which jams at a critical density rho_c < 1. This enables us to explore unjamming by temperature or driving at rho_c < rho < 1. We numerically calculate the relaxation time of the persistence function and its spatial heterogeneity. We disentangle the three different relaxation mechanisms responsible for unjamming when varying density, temperature, and driving strength, respectively. We show that the spatial scale of dynamic heterogeneity depends on density much more strongly than on temperature and driving.