Intermittent behaviour in the Belousov-Zhabotinsky reaction

2014 One of the possible routes to turbulence is the intermittent transition. Below the onset of turbulence regular oscillations exist, and above the onset seemingly regular oscillations are interrupted randomly by large amplitude bursts. This behaviour shows up in the Belousov-Zhabotinsky reaction. Moreover an analysis of the measurements indicates that a so-called « type 1 » transition takes place in this case. Tome 42 No 13 ler JUILLET 1981 LE JOURNAL DE PHYSIQUE-LETTRES J. Physique LETTRES 42 (1981) L-271L-273 1 er 1UILLET 1981, Classification Physics Abstracts 82.20M 82.40 82.60 The possibility of turbulence in chemical kinetics, as suggested by Ruelle [1], has been verified recently [2, 3] for the Belousov-Zhabotinsky (B-Z) reaction. We report here the discovery of an intermittent behaviour in this reaction. Such a behaviour has been seen during the transition to turbulence in thermoconvection experiments [4] and in studies of ordinary equations [5]. In our experiment, the B-Z reaction takes place in an open well stirred tank reactor. Due to stirring, no spatial pattern can develop and the concentrations of the chemical species evolve according to the non linear equations of chemical kinetics, as derived from the mass action law ; this deterministic behaviour is sufficient to produce chaos. The experimental conditions are : reacting volume 28 ml, temperature 39.6 ~C, concentration of reagents before reaction in mol. 1 1 (standard analytical reagent grade without further purification) : A peristaltic pump feeds the reactor at constant adjustable rate. The chemical reaction in the reactor is monitored by the optical density at 340 nm. As this wavelength is absorbed [6] by the Ce4+ ion only, the signal is a sort of « pure quantity » and has been preferred to the redox potential that depends on the concentration of several chemical species. As shown in figure la, when the mean residence time of chemicals in the reactor is 100 min., the optical density oscillates regularly. At higher fluxes (residence time 76 min. in figure I b) the time record changes in a specific manner : seemingly stable oscillations exist which are interrupted from time to time and at random by large peaks. Such a transition from stable periodic behaviour to oscillations interrupted by random bursts denotes an intermittent transition to turbulence [5]. The present transition is well described by «type 1 intermittency » [7], shortly described hereafter. Although detailed modelizations of the B-Z kinetics have been proposed [8], we have not tried to relate them to our observations, since most features of the intermittent transition are model independent. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyslet:019810042013027100 L-272 JOURNAL DE PHYSIQUE LETTRES Fig. 1. [Ce4 +] oscillations recorded as a function of time : a) residence time 100 min. ; b) residence time 76 min. ; c) residence time 35 min.