Synchronized Measurements of Bed-Shear Stress and Flow Velocity in Open Channels with Simulated Vegetation

by Fabi?n L?pez,
Marcelo Garc?a, (M.ASCE),



Document Type: Proceeding Paper

Part of: North American Water and Environment Congress & Destructive Water

Abstract:

Synchronized measurements of shear stresses at the bed and velocities both within and above a simulated plant canopy in an open-channel flow are presented. Traditional (hot-film sensors) and relatively new (acoustic Doppler anemometer) technologies were employed, and wooden dowels have been used to simulate non-emergent, rigid vegetation in a laboratory flume. Results reveal the existence of highly correlated interactions between coherent motions above and within the simulated plants, and the particular relationship between the structures that dominate the turbulent transport of momentum in the fluid and the momentum absorbed by the bed of the channel through skin friction. Cross-correlation analysis allow the determination of geometric as well as kinematic properties of the organized motions responsible for the generation and transport of turbulence. Comparisons are provided with observations in smooth-bed open channels without vegetation.

Subject Headings: Shear stress | Flow measurement | Vegetation | Shear flow | Open channels | River and stream beds | Open channel flow

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