Continuous nonequilibrium transition driven by heat flow

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.

Automated summary

The study reveals an out-of-equilibrium transition in an ideal gas, where supplying energy directly into the system triggers a continuous transition to a state with low-density hot gas on one side of the inner wall and dense cold gas on the other side at critical heat flux. Molecular dynamic simulations confirm this transition, while the introduction of a Helmholtz-like function helps determine the stable positions of the internal wall in the system.