Binary Mixtures in Linear Convection Arrays

Abstract

We numerically investigated the dynamics of a mixture of finite-size active and passive disks in a linear array of two-dimensional convection rolls. The interplay of advection and steric interactions produces a number of interesting effects, like the stirring of a passive colloidal fluid by a small fraction of slow active particles, or the separation of the mixture active and passive colloidal fractions by increasing the motility of the active one, which eventually clusters in stagnation areas along the array walls. These mechanisms are quantitatively characterized by studying the dependence of the diffusion constants of the active and passive particles on the parameters of the active mixture fraction.Binary mixtures of active-passive particles in convection arrays exhibit a conspicuous phase separation into two distinct colloidal fluids for strong self-propulsion of the active fraction. The passive fluid circulating inside the convection rolls and the active one accumulating in stagnation areas along the array walls. On the other hand, a little fraction of weak active particles exert a strong stirring action on a passive colloidal fluid.