Berlin 2015 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 62: Complex Fluids and Soft Matter - Part II (joint session DY, CPP, BP)

CPP 62.2: Talk

Thursday, March 19, 2015, 10:00–10:15, BH-N 334

Dynamics of density excitations in shear-driven, confined binary mixtures — •Sascha Gerloff, Tarlan A. Vezirov, and Sabine H. L. Klapp — Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany

Understanding friction on the microscopic scale is of great interest both from a fundamental and an applicational point of view. An important topic in this context is the appearance of density heterogeneities [1].

Here we perform overdamped Brownian dynamics simulations of a thin film of charged colloidal particles with two different sizes in planar shear flow. The particles interact via a combined Yukawa- and softsphere-potential. The parameters are set to suit experimental data for ludox silica particles, which where previously studied. The one-component system is known to form shear-induced multi-layer configurations in confinement and to show different intra-layer structures which depend on the applied shear rate. [2]

The corresponding two-component system under shear displays density excitations, provided that mixing of the two species is prohibited. We investigate the distribution and motion of these density excitations using voronoi tessellation. The density excitations are then identified as clusters of high local density in the spirit of the Hoshen-Kopelman algorithm.

[1] T. Bohlein, J. Mikhael and C. Bechinger, Nat. Mater. 11, 126-130 (2012).

[2] T. A. Vezirov and S. H. L. Klapp, Phys. Rev. 88, 052307 (2013).