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Coherent Structures in Open-Channel Flows Over a Fixed Dune
Conference proceeding

Coherent Structures in Open-Channel Flows Over a Fixed Dune

Wusi Yue, Ching-Long Lin and Virendra C Patel
Volume 2, Parts A and B, Vol.2, pp.575-582
ASME 2004 Heat Transfer/Fluids Engineering Summer Conference, Charlotte, North Carolina, USA, Jul. 11 - 15, 2004
07/2004
DOI: 10.1115/HT-FED2004-56284

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Abstract

Turbulent open-channel flow over a two-dimensional laboratory-scale dune is studied using large eddy simulation. Free surface motion is simulated using a level set method. Two subgrid scale models, namely dynamic Smagorinsky and dynamic two-parameter models, are employed. The present numerical predictions of mean flow field and turbulence statistics are in good agreement with experimental data. Streaky structures are observed in the wall layer after flow reattachment. Quadrant two events dominate near-wall and near-surface motions. Coherent structures are produced behind the dune crest by strong shear layer riding over the recirculation zone. These tube-like vortical structures are transported downstream with the mean flow and most are destroyed before arriving at the next crest.

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