The influence of concentration-dependent diffusivities on wave stability

Abstract

Investigations on the onset of wave instability in excitable reaction–diffusion media have mainly focused on the effects of reaction kinetics and the relative diffusivity of activator and inhibitor. In this study, we characterize wave stability in a medium in which a diffusion coefficient depends on the local concentration of a reagent. Calculations with a simple CO oxidation model illustrate that the sensitivity of the diffusion coefficient to the concentration can behave like a dynamical parameter to induce transitions between “backfiring” and “regular” propagating pulses. The transition is due to the influence of the variable diffusion process on the refractory zone of wave activity.