Clogging and Transport of Driven Particles in Asymmetric Funnel Arrays

TL;DR

This study uses numerical simulations to explore how particles driven through asymmetric funnel arrays experience clogging, flow, and reentrant pinning, revealing complex behaviors like negative mobility and flow intermittency.

Contribution

It introduces a detailed analysis of clogging and flow regimes in asymmetric funnel arrays, highlighting the effects of particle interactions, drive direction, and temperature on particle dynamics.

Findings

Reentrant pinning occurs at intermediate drives in the hard flow direction.

Clogging is associated with particle clustering in a few plaquettes.

Finite temperatures cause intermittent flow bursts in clogged states.

Abstract

We numerically examine the flow and clogging of particles driven through asymmetric funnel arrays when the commensurability ratio of the number of particles per plaquette is varied. The particle-particle interactions are modeled with a soft repulsive potential that could represent vortex flow in type-II superconductors or driven charged colloids. The velocity-force curves for driving in the easy flow direction of the funnels exhibit a single depinning threshold; however, for driving in the hard flow direction, we find that there can be both negative mobility where the velocity decreases with increasing driving force as well as a reentrant pinning effect in which the particles flow at low drives but become pinned at intermediate drives. This reentrant pinning is associated with a transition from smooth one-dimensional flow at low drives to a clogged state at higher drives that occurs when the particles cluster in a small number of plaquettes and block the flow. When the drive is further increased, particle rearrangements occur that cause the clog to break apart. We map out the regimes in which the pinned, flowing, and clogged states appear as a function of plaquette filling and drive. The clogged states remain robust at finite temperatures but develop intermittent bursts of flow in which a clog temporarily breaks apart but quickly reforms.