Dresden 2017 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 8: Statistical Physics far from Thermal Equilibrium
DY 8.1: Vortrag
Montag, 20. März 2017, 15:00–15:15, ZEU 118
Enhanced nonequilibrium fluctuations of particles driven through a viscoelastic bath — •Johannes Berner1, Juan Ruben Gomez-Solano1, and Clemens Bechinger1,2 — 12. Phykalisches Institut, Universität Stuttgart, Germany — 2MPI for Intelligent Systems, Stuttgart, Germany
Viscoelastic fluids are of great importance in biological systems and in medical and industrial applications. Their flow properties have been extensively studied by bulk rheology [1] and more recently by microrheology [2] using embedded colloidal probes. For instance in passive microrheology the fluctuation-dissipation theorem is used to determine such properties by measuring the thermal fluctuations of the particle position [3]. This is only valid provided that the fluid and the particle are in thermal equilibrium. However this assumption is not trivially satisfied, if the microstructure of the fluid is driven far from equilibrium, e.g. by inducing a local deformation by means of the particle [4, 5]. In this work, we investigate the fluctuations of a colloidal particle driven by optical tweezers at constant velocity through a viscoelastic medium. Unlike in a Newtonian fluid, we observe an enhancement of those fluctuations by driving the fluid out of equilibrium.
[1] Larson R G 1999 The Structure and Rheology of Complex Fluids (New York: Oxford University Press), [2] Squires T. M. and Mason T. G., Annu. Rev. Fluid Mech., 42 (2010) 413, [3] Mason T. G. and Weitz D. A., Phys. Rev. Lett., 74 (1995) 1250, [4] Gomez-Solano J. R. and Bechinger C., EPL, 108 (2014) 54008, [5] Gomez-Solano J. R. and Bechinger C., New J. Physics, 17 (2015) 103032