Negative thermal conductivity of chains of rotors with mechanical forcing

TL;DR

This paper investigates chains of rotors under thermal and mechanical forcing, revealing nonlocal temperature profiles, local equilibrium in long chains, and counterintuitive energy flow behaviors in nonequilibrium steady states.

Contribution

It demonstrates the occurrence of negative thermal conductivity and nonlocal temperature profiles in rotor chains with mechanical forcing, advancing understanding of complex nonequilibrium phenomena.

Findings

Temperature peaks at the chain center indicating nonlocal behavior

Local equilibrium persists in sufficiently long chains

Energy current can increase with an inverse temperature gradient under strong forcing

Abstract

We consider chains of rotors subjected to both thermal and mechanical forcings,in a nonequilibrium steady-state. Unusual nonlinear profiles of temperature and velocities are observed in the system. In particular, the temperature is maximal in the center, which is an indication of the nonlocal behavior of the system. In spite of that, local equilibrium holds for long enough chains. Our numerical results also show that, when the mechanical forcing is strong enough, the energy current can be increased by an inverse temperature gradient. This counterintuitive result again reveals the complexity of nonequilibrium states.