Regensburg 2010 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 35: Posters: Statistical Physics, Evolution, and Networks

BP 35.6: Poster

Donnerstag, 25. März 2010, 17:15–20:00, Poster B2

Extended Fluctuation-Dissipation Theorem for Sheared Colloidal Suspensions — •Boris Lander¹, Thomas Speck², and Udo Seifert¹ — ¹II. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany — ²Department of Chemistry, University of California, Berkeley, CA 94720, USA

We consider suspensions of interacting colloidal particles driven by simple shear flow. For arbitrary strain rates, the recent extension of the fluctuation-dissipation theorem (FDT) to nonequilibrium steady states [1,2] enables us to study the response of single particles (tracer particles) perturbed by a small force. For particles interacting with a screened Coloumb potential, we obtain response and correlation functions through extensive numerical simulations for different densities and strain rates. For higher densities these curves show oscillations, which are explained qualitatively. The time-integrated version of the extended FDT connects the single particle mobility with the diffusion coefficient through an integrated excess function. In addition, we analyze features of this system analytically in the simple model of a single particle in a harmonic potential driven by shear flow.

[1] T. Speck and U. Seifert, Europhys. Lett. 74, 391, (2006)

[2] T. Speck and U. Seifert, Phys. Rev. E 79, 040102(R), (2009)