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DY: Fachverband Dynamik und Statistische Physik

DY 22: Granular matter / contact dynamics I

DY 22.1: Vortrag

Mittwoch, 28. März 2007, 15:45–16:00, H2

Ripples in weakly turbulent flows in an annular channel — •Andreas Wierschem¹, Tobias Edtbauer^1,2, Christopher Groh², Christoph Krülle², Ingo Rehberg², and Nuri Aksel¹ — ¹Technische Mechanik und Strömungsmechanik, Universität Bayreuth, D-95440 Bayreuth — ²Experimentalphysik V, Universität Bayreuth, D-95440 Bayreuth

One of the most conspicuous examples of pattern formation in nature are the dunes and ripples formed in sand, either by wind or by surface waves and shear flows in water. The environmental flow conditions are usually highly turbulent. In laboratory studies, research has also mainly been focused on the formation of ripples and dunes in fully turbulent flow. Here, we present an experimental study of ripple generation in an annular channel at rather low Reynolds numbers in weakly turbulent flow. We detect the granular motion, the resulting ripples, and characterize the velocity field in the overlying fluid that provokes the ripple formation.