Dresden 2006 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 27: Granular Matter and Contact Dynamics II

DY 27.3: Vortrag

Dienstag, 28. März 2006, 17:00–17:15, SCH 251

Ripple generation under shear — •Andreas Wierschem¹, Christof Krülle², Ingo Rehberg², and Nuri Aksel¹ — ¹Technische Mechanik und Strömungsmechanik, Universität Bayreuth, D-95440 Bayreuth — ²Experimentalphysik V, Universität Bayreuth, D-95440 Bayreuth

The generation of ripples in desserts or at beaches by wind or tidal currents is a paradigm of instabilities in granular material under shear. Research has been focused mainly on the surface profile of the granular layer, describing the ripples and their instability in terms of global parameters. Here, we present an experimental study of the velocity field in the overlying fluid. We characterize the field at onset of ripple generation and show how the ripples exert a feedback on the fluid flow in an annular-ring geometry with driven upper lid.