Quantification of Turbulence in the Belousov−Zhabotinsky Reaction by Monitoring Wave Tips

Abstract

We analyze experimentally the tip's motion under conditions in which waves are disorderly distorted by “ripples”. We thus reduce a complex spatiotemporal phenomenon to a purely temporal process, which we then quantify by the maximum Lyapunov exponent. In contrast to the periodic or quasiperiodic tip meanderings reported so far, we present evidence for chaotic tip motion in the case of ripples induced by oxygen in the ferroin- and the ruthenium-catalyzed reactions. For ripples induced by light in the ruthenium-catalyzed reaction, we find absence of chaos in the tip; this points to significant mechanistic differences between the action of light and that of oxygen. Our findings are corroborated by the determination of the power spectra. Chaotic meandering is relevant to spiral drift techniques owing to the essential role of the interaction of the spiral tip with external drift-inducing stimuli.