MPIDS Seminar: Collective dynamics of active semi-flexible filaments
10:15 - 11:15
Dr. Prathyusha Kokkoorakunnel Ramankutty
Department of Living Matter Physics, MPIDS
Max-Planck-Institut für Dynamik und Selbstorganisation (MPIDS)
Prandtl Lecture Hall
Biological systems like actin or microtubule filaments driven by molecular motors inside a cytoskel-eton and bacteria gliding on a substrate are flexible slender bodies which can consume energy locally and are capable of spontaneous directed motion. They can exhibit non-equilibrium collective behav-iour which is absent in conventional passive polymers, where the dynamics are dominated by thermal fluctuations. The flexible structure and activity make their collective behaviour inherently very com-plex.
This talk is based on our recent work on a dense planar layer of active semi-flexible filaments using Langevin dynamics simulations . In this study active filament is modelled as an inextensible, semi-flexible, self-avoiding polymer, with a propulsion force acting along the contour of the filament. We showed the emergence of various collective phases a) owing melt phase b) swirl c) segregated phase and d) spirals (see Fig) as a function of active force and thermal persistence length of filaments. Most strikingly, we identify an activity-driven cross-over from a state of coherently owing bundles of fila-ments to a phase with no global ow, formed by filaments coiled into rotating spirals. This suggests a mechanism where the system responds to activity by changing the shape of active agents, an effect with no analogue in systems of active particles without internal degrees of freedom.