Colloidal clustering and diffusion in a convection cell array

We numerically investigated the clustering of a uniform suspension of finite-size disks in a linear array of two-dimensional convection cells. We observed that, due to steric interactions, the disks tend to form coherently rotating spatial structures at the center of each cell, as a combined effect of advection and pair collisions. Micellar, ring-like and hexatic patterns emerge in the deterministic regime, depending on the suspension density, but dissolve in the presence of thermal fluctuations. Moreover, pair collisions suffice to activate cell crossings even by noiseless disks and, therefore, cause athermal diffusion. The robustness of such collision induced effects is studied against the opposing action of thermal noise, transverse biases, and particle self-propulsion.

Automated summary

We numerically investigated the clustering of finite-size disks in a linear array of two-dimensional convection cells. The disks tend to form coherently rotating structures at the center of each cell due to steric interactions and pair collisions. Different patterns emerge depending on the suspension density, but thermal fluctuations dissolve them. Pair collisions activate cell crossings and cause athermal diffusion even by noiseless disks. The robustness of these collision induced effects is studied against thermal noise, transverse biases, and particle self-propulsion.