Dynamics and Synchronization of Surface Active Flow Driven Droplets

Active droplets which can autonomously locomote are of both fundamental interest and practical importance. Due to the action of the active agents in the droplets, surface active flow will arise, which can drive the droplets to propel. We investigate the dynamics of droplets above a no-slip bottom wall, driven by neutral swimmers on their surfaces. For a single droplet, its trajectories exhibit petal-like circular motions. Synchronization phenomena are observed in the presence of multiple droplets, due to translation-rotation hydrodynamic coupling. Our work sheds light on understanding the surface flow mediated autonomous motion of active droplets.