Continuous non-equilibrium transition driven by the heat flow

TL;DR

This paper reports the discovery of a continuous out-of-equilibrium transition in an ideal gas system driven by heat flow, characterized by a phase change in density and temperature distribution across a movable wall.

Contribution

The study introduces a novel out-of-equilibrium transition driven by heat flux and proposes a Helmholtz-like function to describe the stable states, supported by molecular dynamics simulations.

Findings

Identified a critical heat flux inducing a phase transition

Confirmed the transition in both ideal and interacting gas systems

Proposed a thermodynamic-like function to characterize stationary states

Abstract

We discovered an out-of-equilibrium transition in the ideal gas between two walls, divided by an inner, adiabatic, movable wall. The system is driven out-of-equilibrium by supplying energy directly into the volume of the gas. At critical heat flux, we have found a continuous transition to the state with a low-density, hot gas on one side of the movable wall and a dense, cold gas on the other side. Molecular dynamic simulations of the soft-sphere fluid confirm the existence of the transition in the interacting system. We introduce a stationary state Helmholtz-like function whose minimum determines the stable positions of the internal wall. This transition can be used as a paradigm of transitions in stationary states and the Helmholtz-like function as a paradigm of the thermodynamic description of these states.