IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 35th IAHR Congress - Chengdu (2013) : THEME 4 - HYDRO-ENVIRONMENT : Observations on Flow and Deposited Configuration around Single Bending Submerged Flexible Vegetation
Observations on Flow and Deposited Configuration around Single Bending Submerged Flexible Vegetation
Author : Su-Chin Chen, Je-Wei Liao, Hsun-Chuan Chan and Yi-Chiung Chao
This study experimentally investigated the effects of bending submerged flexible vegetation on the characteristics of flow and configuration of deposition. Bending submerged flexible vegetation was produced using a plastic pipe and films which were 20 cm long. The experimental flow velocitieswere performed for three sediment critical velocities (Vc) experiments, 0.8 Vc, Vc, and 1.2 Vc. Vertical distributions of time-averaged velocity and turbulent intensity at various streamwise distances were measured with an acoustic Doppler velocimeter (ADV). The flow characteristics around the bending submerged vegetation were analyzed. The results show that the velocities reduced around the vegetation as the water flow passed through it; in particular, the flow velocities reduced dramatically in the middle and at the end sections of the vegetation because eddies develop at the front of the vegetation and flow along the vegetation toward downstream. It induced the turbulence intensity and the flow kinetics disappeared gradually. A scour hole formed, which was affected by the local scour at the front of the vegetation; the sediment was then transported downstream as the flow conditions on Vc, and 1.2 Vc. The sediment deposited on the low velocity zone was influenced by the disturbance to diminish the turbulence intensity under the vegetation; in addition, the dune forming appeared progressively. The dune height, the length of the deposition zone, the horizontal distance of the dune crest increased with an increasing flow rate.
File Size : 525,667 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 35th IAHR Congress - Chengdu (2013)
Date Published : 18/07/2016
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