A self-enhanced mobility mechanism drives the spontaneous emergence and transformation of vortex patterns

Active systems frequently exhibit remarkable self-organization phenomena, characterized by transition from disorder to order. Yet, the underlying mechanisms driving the spontaneous emergence and transformation of vortex patterns within these systems remain poorly understood. In this study, we introduce a chiral self-propelled rod (CSPR) model that integrates a self-enhanced mobility mechanism, wherein the propulsion speed of individual particles is positively regulated by the local alignment and density of their neighbors. Using this model, we successfully reproduce a wide spectrum of vortex self-organization behaviors in chiral active systems. Our findings reveal that the self-enhanced mobility mechanism plays a pivotal role in driving the spontaneous formation of vortices and mediating the transitions between distinct vortex patterns by modulating their size and number. Furthermore, we identify a non-monotonic dependence of the system mean velocity and vorticity on the aspect ratio of the rods, with an optimal aspect ratio that maximizes both quantities. Finally, through an analysis employing three correlation functions, we demonstrate that variations in both self-enhanced mobility and aspect ratio markedly affect the angular and spatial correlations within vortex structures. These simulation results align well with experimental observations, offering theoretical insights to bridge collective dynamics of active microswarms with practical applications in bio-inspired microrobotic systems.