  Controlling the motion of active matter is a central issue that has recently
garnered significant attention in fields ranging from non-equilibrium physics
to chemical engineering and biology. Distinct methods for controlling active
matter have been developed, and physical confinement to limited space and
active matter with broken rotational symmetry (chirality) are two prominent
mechanisms. However, the interplay between pattern formation due to physical
constraints and the ordering by chiral motion needs to be better understood. In
this study, we conduct numerical simulations of chiral self-propelled particles
under circular boundary confinement. The collective motion of confined
self-propelled particles can take drastically different forms depending on
their chirality. The balance of orientation changes between particle
interaction and the boundary wall is essential for generating ordered
collective motion. Our results clarify the role of the steric boundary effect
in controlling chiral active matter.
