Aggregate morphing of self-aligning soft active disks in semi-confined geometry

Abstract

We study the dependence of alignment and confinement on the aggregate morphology of self-aligning soft disks(particles) in a planer box (two dimensional) geometry confined along y direction using Langevin dynamics simulations. We show that when the box width decreases, the aggregate wall accumulation becomes non-uniform and displays non-monotonic behaviour in terms of phase behavior and height of these aggregates with an increase in alignment strength. Additionally, we identify two distinct categories of wall aggregates: layered and non-layered structures each exhibiting distinct local structural properties. For non-layered structures, local speed of the particles stay nearly constant as we move away from the boundary, while for layered structures, it increases with distance from the boundary. Our analysis shows that active pressure difference is a useful indicator for different aggregate morphologies and the peaks in the pressure curve are indicative of the average and minimum height of the structure.