Berlin 2015 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 44: Pattern Formation

DY 44.1: Talk

Thursday, March 19, 2015, 09:30–09:45, BH-N 333

Feedback control and semi-laning in confned colloidal suspensions — •Tarlan A. Vezirov, Sascha Gerloff, and Sabine H. L. Klapp — Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany

Colloidal particles under the combined influence of an external driving force and restricted geometry exhibit a wealth of non-linear phenomena, which are relevant in diverse fields such as directed particle transport, sorting mechanisms and friction phenomena at the nanoscale. We perform Brownian Dynamic simulations of strongly confined systems of charged colloidal particles interacting via a combined soft-sphere and Yukawa potential. Under an external shear flow such systems display a sequence of states characterised by pinning, shear-induced melting and reentrant ordering into a moving hexagonal state [1]. Here we focus on the following situations: First, we consider a crystalline bilayer. By adding a feedback equation of motion we are able to stabilise specific properties such as the degree of hexagonal ordering or the shear stress. This opens the route for a deliberate control of friction properties of the system [2]. Second, we consider an open-loop controlled trilayer system. Besides the three states already observed in the bilayer system [1] we observe a novel state, which is characterized by the separation of the middle layer into two sublayers with opposite velocities. This is enabled by the formation of microlanes.

[1] T. A. Vezirov and S. H. L. Klapp, Phys. Rev. E 88, 5 (2013). [2] T. A. Vezirov, S. Gerloff and S. H. L. Klapp, Soft Matter DOI: 10.1039/c4sm01414f (2014).