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Open AccessTechnical Note

Local Scour Near Flexible Flow Deflectors

1
College of Civil Engineering, Tongji University, Shanghai 200092, China
2
State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiaotong University, Shanghai 200240, China
3
Zhejiang Institute of Hydraulics and Estuary, Hangzhou 310020, China
4
Department of Ocean and Mechanical Engineering, Florida Atlantic University, Boca Raton, FL 33431, USA
*
Author to whom correspondence should be addressed.
Water 2020, 12(1), 153; https://doi.org/10.3390/w12010153
Received: 2 November 2019 / Revised: 2 January 2020 / Accepted: 3 January 2020 / Published: 4 January 2020
(This article belongs to the Section Hydraulics and Hydrodynamics)
Rigid flow deflectors are usually used on water flow beds to protect engineering structures such as breakwater in coasts and to regulate flow routes in open channels. To reduce its side-effects, i.e., local scour at the toe of deflectors, a flexible flow deflector is proposed, and the corresponding local scour was investigated in this study. A flume experiment was conducted to investigate local scour. To show the advantage of flexible deflectors, a control experimental test was also conducted using a traditional rigid deflector under the same blockage area configuration and the same flow conditions. The flow field near the flexible deflector was also measured to reveal the local flow field. The results show that the bed-scour develops near the toe edges of both flexible and rigid deflectors, but the maximum and averaged scour depths for the flexible deflector are smaller. This advantage of flexible deflector in scour depth is mainly caused by its prone posture, which induces the upward stretching and enlarging horizontally rotating vortex and the upward shifted vertically rotating vortex. The former dissipates more turbulent energy and the latter results in smaller bed shear stress, which lead to smaller scour depth directly. In addition, the up- and down-swaying movement of the flexible deflector can also assistant to dissipate more turbulent energy, thereby damping the intense of the horseshoe vortices and thus weakening scour depth as well. The results of this study provide an elementary understanding on the mechanisms of a flexible flow structure and an alternative deflector-device to reduce scour depth. View Full-Text
Keywords: flexible flow deflector; scour depth; horseshoe vortex flexible flow deflector; scour depth; horseshoe vortex
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MDPI and ACS Style

Xie, L.; Zhu, Y.; Li, H.; Li, Y.-h.; Yang, Y.; Su, T.-c. Local Scour Near Flexible Flow Deflectors. Water 2020, 12, 153. https://doi.org/10.3390/w12010153

AMA Style

Xie L, Zhu Y, Li H, Li Y-h, Yang Y, Su T-c. Local Scour Near Flexible Flow Deflectors. Water. 2020; 12(1):153. https://doi.org/10.3390/w12010153

Chicago/Turabian Style

Xie, Liquan; Zhu, Yehui; Li, Huang; Li, Yan-hong; Yang, Yuanping; Su, Tsung-chow. 2020. "Local Scour Near Flexible Flow Deflectors" Water 12, no. 1: 153. https://doi.org/10.3390/w12010153

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