FLUCTUATION-DOMINATED KINETICS UNDER STIRRING

We investigate the effects of stirring on the kinetics of the A + B -- > 0 reaction under stoichiometrical conditions in 2D. We consider both a steady eddy-lattice flow and a random flow mimicking turbulence. In both situations complex decay patterns are detected. Only an intermed iate stage of the reaction is dominated by mixing. The long-time behav ior shows fluctuation-dominated kinetics, c(t) proportional to t(-1/2) , governed by effective diffusion. For the case of an eddy-lattice flo w a very slow intermediate regime emerges, c(t) proportional to t(-1/4 ), which is associated with the closed topology of flow lines.