KINETICS OF THE A-]0 REACTION UNDER STEADY AND TURBULENT FLOWS(B)

We consider the kinetics of the two-dimensional, stoichiometric A + B --> O reaction under external flows, for which we use two models: Firs t a Steady flow, which consists of an array-of eddies; second a time-d ependent, stochastic flow which mimics turbulent fluid motion. We foll ow the reaction numerically and detect in both situations complex deca y patterns, which obey different power-laws at short, intermediate and long times: While the initial stage of the reaction is dominated by m ixing, c(t) proportional to t(-1), the long-time behavior shows fluctu ation-dominated kinetics, c(t) proportional to t(-1/2). In the case of the eddy-lattice-flow a very slow intermediate regime, with c(t) prop ortional to t(-1/4), emerges. This regime is explained in the framewor k of an analytical model for mixing along closed-flow lines. (C) 1996 American Institute of Physics.