Dresden 2006 – wissenschaftliches Programm
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AKB: Biologische Physik
AKB 24: Brownian Motion and Fluctuation Theorems
AKB 24.3: Vortrag
Donnerstag, 30. März 2006, 17:45–18:00, ZEU 255
Short-time inertial response of viscoelastic fluids: observation of vortex propagation — •Maryam Atakhorrami1, Gijsberta H. Koenderink2, Daisuke Mizuno1, Tanniemola Liverpool3, Christoph F. Schmidt1, and Frederick C. MacKintosh1 — 1Dept. Physics, Vrije Universiteit, Amsterdam, NL — 2Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA — 3Department of Applied Mathematics, School of Mathematics, University of Leeds, Leeds, LS2 9JT, UK
We probe the response of viscous and viscoelastic fluids on micrometer and microsecond length and time scales using two optically trapped beads. In this way we resolve the flow field, which exhibits clear effects of fluid inertia. Specifically, we resolve the short time vortex flow and the corresponding motion of this vortex, which propagates diffusively for simple liquids. For viscoelastic fluids, this propagation is shown to be faster than diffusive and the displacement correlations reflect the frequency dependent shear modulus of the medium. The phenomenon is related to long-time tails in scattering experiments.