Nonequilibrium Steady States for Certain Hamiltonian Models

TL;DR

This paper numerically investigates nonequilibrium steady states in Hamiltonian models with energy exchange, extending previous predictions to 2D systems and analyzing effects like memory and finite-size impacts on energy and particle profiles.

Contribution

It extends the prediction scheme for energy and particle profiles to 2D Hamiltonian models with various boundary conditions and examines the influence of memory and finite-size effects.

Findings

Prediction schemes remain accurate across different lattice geometries.

Memory and finite-size effects are context-dependent and can be minimized with correction schemes.

Directional bias due to memory influences local energy and particle profiles.

Abstract

We report the results of a numerical study of nonequilibrium steady states for a class of Hamiltonian models. In these models of coupled matter-energy transport, particles exchange energy through collisions with pinned-down rotating disks. In [Commun. Math. Phys. 262 (2006)], Eckmann and Young studied 1D chains and showed that certain simple formulas give excellent approximations of energy and particle density profiles. Keeping the basic mode of interaction in [Eckmann-Young], we extend their prediction scheme to a number of new settings: 2D systems on different lattices, driven by a variety of boundary (heat bath) conditions including the use of thermostats. Particle-conserving models of the same type are shown to behave similarly. The second half of this paper examines memory and finite-size effects, which appear to impact only minimally the profiles of the models tested in [Eckmann-Young]. We demonstrate that these effects can be significant or insignificant depending on the local geometry. Dynamical mechanisms are proposed, and in the case of directional bias in particle trajectories due to memory, correction schemes are derived and shown to give accurate predictions.