Dresden 2009 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 20: Focused Session: Pattern formation in colloidal and granular systems
DY 20.2: Topical Talk
Donnerstag, 26. März 2009, 10:00–10:30, HÜL 386
Non-equilibrium aggregates in confined systems of self-propelling colloidal rods — •Rik Wensink1 and Hartmut Löwen2 — 1Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom — 2Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität-Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
Swimming microorganisms, birds and fish often move collectively in large groups with spontaneous liquid crystalline order. Considerable research activity has been devoted in recent years to understand the origin of flocks and swarms in terms of simple models of self-propelled particles. In these models, ``active'' rods are driven by their own motor along the rod orientation axis and dissipate energy in the suspending medium. While the bulk behaviour of ``active matter" is by now well understood, very little is known about the effects of system boundaries and confining geometries.
We have studied the non-equilibrium collective behavior of self-propelled colloidal rods moving in narrow channels by means of Brownian dynamics computer simulation and dynamical density functional theory. We observe an aggregation process in which rods self-organize into compact clusters that are transiently jammed at the channel walls. In the early stages of the aggregation process, fast-growing hedgehog-like wall clusters are formed which are virtually immobile. At later stages, most of these clusters dissolve and mobilize into nematized aggregates moving along the channel walls.