Fluctuation-Dominated Kinetics under Stirring

We investigate the effects of stirring on the kinetics of the $A+B\to 0$ 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 intermediate stage of the reaction is dominated by mixing. The long-time behavior shows fluctuation-dominated kinetics, $c\left(t\right)\propto t^{-1/2\mathrm{}}$, governed by effective diffusion. For the case of an eddy-lattice flow a very slow intermediate regime emerges, $c\left(t\right)\propto t^{-1/4\mathrm{}}$, which is associated with the closed topology of flow lines.