Reentrant Melting of Lanes of Rough Circular Discs

TL;DR

This study investigates the formation and re-entrance of lane states in a binary suspension of rough circular particles under external drive, revealing that particle roughness and contact friction critically influence lane dynamics in non-equilibrium conditions.

Contribution

It demonstrates the re-entrant nature of lane formation driven by particle roughness and external force, highlighting the role of contact friction in non-equilibrium phase transitions.

Findings

Oppositely moving lanes form only within a specific external drive range.

No-lane states reappear at both low and high external drives.

Particle roughness and contact friction are key factors in lane re-entrance.

Abstract

We consider binary suspension of rough, circular particles in two dimensions under athermal conditions. The mean density of the system is kept constant. The suspension is subject to a time-independent external drive in response to which one half of the particles are pulled along the field direction whereas the other half is pushed in the opposite direction. Simulating the system with different magnitude of external drive in steady state, we obtain oppositely moving macroscopic lanes only for a moderate range of external drive. Below as well as above the range we obtain states with no lane. Hence we find that no-lane state re-enters along the axis of the external drive in the non-equilibrium phase diagram corresponding to the laning transition, with varying roughness of individual particles and external drive. Inter-particle friction (contact dissipation) due to the roughness of the individual particle is the main player behind the re-entrance of no-lane state at high external drives.