Coordinated motion of active filaments on spherical surfaces*

Active filaments (slender, self-deforming, and microscopic elastic bodies) are prevalent in biological settings with the prime examples being cilia and flagella.  For cilia in particular, which can appear in dense arrays, their resulting motions are coupled through the surrounding fluid, as well as through the surfaces to which they are attached.  In this talk, I will present numerical simulations exploring the coordinated motion of hundreds of active filaments and how it depends on the driving force, density of filaments, as well as the attached surface.  We find that when the surface is spherical, its topology introduces defects in the coordinated motion which alter filament motion, especially in their vicinity.  Further, when the sphere is not held fixed, its motion feeds back onto the filaments, leading to more profound changes in their motion and the emergence of a new coordinated state.