Fluctuation-induced and Nonequilibrium-induced Bifurcations in a Thermochemical System

Abstract

We study the Semenov thermochemical model at different levels of description. This simple model of combustion includes the description of slow oxidation with stabilization of the system around a low temperature and thermal explosion leading the system to a high temperature. The results of the mesoscopic description based on the master equation and microscopic simulations of the particle dynamics reveal deviations from the macroscopic deterministic dynamics. Fluctuation effects observed in small systems change the domains of mono- and bistability of the system. These are noise-induced bifurcations, already known in isothermal chemical systems. Another effect is related to the departure of particle velocity distribution from its equilibrium shape. The departure from partial equilibrium originating at the level of the velocity distribution also leads to changes of the bifurcation diagram. By analogy, we call this phenomenon a nonequilibrium-induced bifurcation.