The dynamics of in-silico active filamentous elastic swimmers explored using Brownian dynamics simulations

Slender elastic filaments when continuously deformed by active or actuating forces fields can move persistently. In filament-motor assays for instance, animating forces act directionally along the filament; forces thus follow the ensuing filament motion thereby driving and sustaining the deformation. Here, we study the spatiotemporal dynamics of a computationally minimal swimmer - an active elastic filament attached to a viscous cargo that can move in a plane. Locomotion is achieved via competition between activity, elasticity, dissipation and boundary constraints. Examination of the emergent phase space allows us to identify three distinct stable locomoting forms attained by the filament-cargo complex - straight, rotation, and oscillatory flutter. We show that transitions between these states may be trigerred by ramping or dampening noise, by tuning global elasticity and by adjusting the type or softness of the connection between the cargo (head) and the filament (tail). Furthermore, these in-silico swimmers move as soft blobs with effective spatial extent primarily determined by a combination of activity and elasticity. Our results allow for a nuanced understanding of the patterns seen in assays and also offer rules that may guide the design of synthetic soft microswimmers.