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Clear Water Local Scour and Flow Field around Various Submerged Flexible and Solid Structures

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2010 Pittsburgh, Pennsylvania, June 20 - June 23, 2010  1008779.(doi:10.13031/2013.29887)
Authors:   Yi-Ming Kuo, Su-Chin Chen
Keywords:   flexible structure, solid structure, local scour, vegetation, turbulent kinetic energy.

The acoustic Doppler velocimetry (ADV) data were applied to plot the vertical distributions of three-dimensional velocities and the turbulent contours. Experimental results indicate that arrangement density, structural material (flexible or solid), and the sidewall effect are the main factors impacting turbulent kinetic energy and the morphology of scour holes. For most flexible structures, the maximum turbulent kinetic energy near the bed surface increased with the arrangement density. For the same structure, the depth and the magnitude of the lateral expansion of the scour hole also increased with the arrangement density. The flexible vegetation enlarged the longitudinal length of the scour hole due to deflection and porous characteristics. The larger volumes of erosion found in the upstream and middle sections of solid structures compare to those in flexible structures. The deflection of flexible structures with the porous characteristic transported the turbulent kinetic energy downstream, reduced the turbulent kinetic energy near the sediment bed, and increased the stability of the structures. Therefore, flexible materials have the ability to protect the bank and the bed of a river, which makes them a good alternative design in the management and restoration of rivers.

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