Response of Velocity and Turbulence to Abrupt Changes from Smooth to Rough Beds in Open-channel Flows

by Iehisa Nezu, (M.ASCE), Kyoto Univ, Kyoto, Japan,
Akihiro Tominaga, Kyoto Univ, Kyoto, Japan,

Abstract: Response of velocity distribution and turbulence characteristics to abrupt changes of bed roughness have been investigated experimentally with two-component laser Doppler anemometer (LDA). Of particular significance is the overshooting property of bed shear stress immediately downstream of roughness discontinuity in open-channel flows. These variations of open-channel turbulence due to the abrupt changes of bed roughness were well predicted numerically by making use of the k-ɜ model.

Subject Headings: Hydraulic roughness | River and stream beds | Turbulence | Shear stress | Lasers | Doppler systems | Open channels | Open channel flow

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