Aggregation of Active Brownian Particles on porous, circular walls

Abstract

We study the motility-induced aggregation of active Brownian particles on a porous, circular wall. We observe that the morphology of aggregated dense-phase on a static wall depends on the wall porosity, particle motility, and the radius of the circular wall. Our analysis reveals two morphologically distinct, dense aggregates; a connected dense cluster that spreads uniformly on the circular wall, and a localized cluster which breaks the rotational symmetry of the system. These distinct morphological states are similar to the transitions obtained in planar, porous walls. We systematically analyze the parameter regimes where the different morphological states are observed. We further extend our analysis to motile circular rings and show that the ring propels ballistically due to the force applied by the active particles when the dense particle aggregates form a localized cluster, thus spontaneously extracting effective work from the system.