Nambu Nonequilibrium Thermodynamics and the Lyapunov Structure of Open Systems (opens in new tab)

In open nonequilibrium systems, the thermodynamic entropy of a subsystem is not generally a Lyapunov function. Even during relaxation toward equilibrium, it may decrease temporarily because of exchanges with external reservoirs. This raises a basic question: what thermodynamic quantity, if any, organizes irreversible relaxation in an open system? We address this question using an explicit open-piston model coupled to both a pressure reservoir an...