Dynamical Motion of Surface Active Flow Driven Droplets

Active droplets which can autonomously locomote are of both fundamental interest and of practical importance. Due to the action of the active agents in the droplet, hydrodynamic flows may arise on its interface, and can drive the droplet to propel. However, our current understanding of how surface active flows determine the dynamical modes of the droplet remains elusive to date. To address this question, here we consider the dynamical motion of a droplet driven by microswimmers self-propelling on its interface. Specifically, we use rigid multiblob method to simulate the dynamic trajectory of a single spherical droplet near a no-slip wall mobilized by active point-like particles on its interface. Interestingly, we find that the simulated trajectories exhibit rich dynamical modes consisting of circular, helical, or petal-like circular motions. These modes can be controlled by the initial pitch angle and swimmer configurations. The dynamical behaviors are further quantitatively analyzed and explained. Our work sheds light on understanding the surface flow mediated autonomous motion of active droplets.