Experiment in Coupled Chemical Oscillators Asymmetric Coupling Stabilizes Anti-Phase Mode

Minoru Yoshimoto¹, Kenichi Yoshikawa², Yoshihito Mori³ and Ichirou Hanazaki³

¹Faculty of Science, Nagoya University, Nagoya 464-01, Japan
²Graduate School of Human Informatics, Nagoya University, Nagoya 464-01, Japan
³Institute for Molecular Science, Okazaki 444, Japan

(Received May 9, 199 1; Accepted November 1, 1991)

Keywords: The Belousov-Zhabotinsky Reaction, Entrainment, Asymmetric Coupling, CSTR

Abstract. In the present study, the oscillatory Belousov-Zhabotinsky reaction was studied in a pair of continuous-flow stirred tank reactors coupled through mass transfer between the reactors. The coupling strength was quantitatively controlled by changing the flow rate between the reactors with a peristaltic pump. Here, the effects of "asymmetric" coupling on the mode of interference between the oscillators have been extensively studied. In order to ascertain the presence of synchronization or mode locking, interference between the chemical oscillators with slightly different natural frequencies was examined. Depending upon the coupling strength, and also upon the degree of "asymmetry" in the interaction, three different modes were observed: quasiperiodic state, anti-phase synchronization, and in-phase synchronization. It has been found that the parameter space of coupling strength for anti-phase synchronization in "asymmetric" coupling is greater than that in "symmetric" coupling. The above experimental trend was discussed in relation to the results of numerical simulations based on coupled nonlinear differential equations.