Driving kinetically constrained models into non-equilibrium steady states: structural and slow transport properties

TL;DR

This paper investigates the non-equilibrium steady states of a 2D kinetically constrained model under external driving, revealing how structural formations influence transport properties and resistance behavior in dense, viscous-like systems.

Contribution

It provides a detailed numerical analysis of the microscopic dynamics and structural features of the driven Kob-Andersen model, linking spatial structures to transport regimes and resistance transitions.

Findings

Transition from positive to negative resistance explained by particle trapping structures.

Spatial correlations and dynamic heterogeneities are characterized at high density.

Structural formations intermittently trap particles, slowing down dynamics.

Abstract

Complex fluids in shear flow and biased dynamics in crowded environments exhibit counterintuitive features which are difficult to address both at theoretical level and by molecular dynamic simulations. To understand some of these features we study a schematic model of highly viscous liquid, the 2D Kob-Andersen kinetically constrained model, driven into non-equilibrium steady states by a uniform non-Hamiltonian force. We present a detailed numerical analysis of the microscopic behavior of the model, including transversal and longitudinal spatial correlations and dynamic heterogeneities. In particular, we show that at high particle density the transition from positive to negative resistance regimes in the current vs field relation can be explained via the emergence of nontrivial structures that intermittently trap the particles and slow down the dynamics. We relate such spatial structures to the current vs field relation in the different transport regimes.