Cooperativity and hydrodynamic interactions in externally driven semiflexible filaments

Abstract

We describe a simple simulation method that describes the hydrodynamics of semiflexible filaments immersed in a low Reynolds number fluid and analyze how multiple body cooperativity emerges due to the presence of hydrodynamic interactions (HI). We study the sedimentation of ensembles of filaments under an external force and also consider the propulsion of filaments subject to simple periodic driving. In both cases the dynamics shows qualitative differences due to the presence of HI. For sedimentation, the effects include cooperative velocity and instabilities that can be understood from the interplay of deformations due to flexibility and hydrodynamic forces. The motion of swimmers is more complex, and shows both positive and negative cooperation depending on distance, frequency of drive, and flexibility.