Active Nematic Flows in Confinments with topologically defective Boundaries

Active Nematic flows exhibit chaotic nature at large scales. However, at smaller scales, we are discovering that this chaos can be tamed by restricting the flow to confined regions. In circular geometries, we have seen that the flow appears to behave quasi-periodically, and the motion of the defects form various braiding structures. We aim to untangle this behavior further by studying the motion of the defects in channel geometries. By winding the director field at the boundaries, we see a localization of the -1/2 defects and the corresponding +1/2 pairs hovering and hopping over the -1/2 defects but never annihilating. We have also observed the localization of +1/2 and -1/2 defects at a fixed distance relative to each other close to the boundaries, which often gets disrupted by free-flowing defect charges in the bulk.

Understanding this behavior, namely, the localization of -1/2 charge, the duet of +1/2 and -1/2 defects holding stationary, and the breaking of the duet due to collision with free-flowing charges in the context of channels has the potential to form more complex circuits through Active Nematics. With our study, we aim to provide the necessary physical constraints that lead to said defect dynamics, and provide a mechanistic and pragmatic understanding of Active Nematic flows in confined channels.