EXPERIMENTAL STUDY OF IMMERSED PLATES USED AS BREAKWATERS

1988 ◽  
Vol 1 (21) ◽  
pp. 168
Author(s):  
Alain Drouin ◽  
Yvon Ouellet

Under certain wave conditions, an immersed plate which is free to move horizontally produces what has already been called the oscillating water wall phenomenon. When this happens, the plate and the volume of fluid located under the plate move back and forth and then behave as a wave reflector. This type of breakwater was studied in a wave flume with monochromatic and irregular wave trains. Tests have provided a better understanding of the influence of certain parameters that define a plate and the hydraulic conditions under which the plate is used. Results show some interesting efficiencies and also transfert of the energy to harmonic frequencies.

2021 ◽  
Vol 224 ◽  
pp. 108738
Author(s):  
Yoon-Jin Ha ◽  
Kyong-Hwan Kim ◽  
Bo Woo Nam ◽  
Sa Young Hong ◽  
Hyunjoe Kim

2020 ◽  
Vol 99 ◽  
pp. 102141
Author(s):  
Zhen Liu ◽  
Chuanli Xu ◽  
Hongda Shi ◽  
Na Qu

Author(s):  
Li YIPING ◽  
Desmond Ofosu ANIM ◽  
Ying WANG ◽  
Chunyang TANG ◽  
Wei DU ◽  
...  

This paper presents a well-controlled laboratory experimental study to evaluate wave attenuation by artificial emergent plants (Phragmites australis) under different wave conditions and plant stem densities. Results showed substantial wave damping under investigated regular and irregular wave conditions and also the different rates of wave height and within canopy wave-induced flows as they travelled through the vegetated field under all tested conditions. The wave height decreased by 6%–25% at the insertion of the vegetation field and towards the downstream at a mean of 0.2 cm and 0.32 cm for regular and irregular waves respectively. The significant wave height along the vegetation field ranged from 0.89–1.76 cm and 0.8–1.28 cm with time mean height of 1.38 cm and 1.11 cm respectively for regular and irregular waves. This patterns as affected by plant density and also location from the leading edge of vegetation is investigated in the study. The wave energy attenuated by plant induced friction was predicted in terms of energy dissipation factor (fe) by Nielsen’s (1992) empirical model. Shear stress as a driving force of particle resuspension and the implication of the wave attenuation on near shore protection from erosion and sedimentation was discussed. The results and findings in this study will advance our understanding of wave attenuation by an emergent vegetation of Phragmites australis, in water system engineering like near shore and bank protection and restoration projects and also be employed for management purposes to reduce resuspension and erosion in shallow lakes.


2018 ◽  
Vol 18 (3) ◽  
pp. 93-101
Author(s):  
Mohamed A. Ashour ◽  
Tawab E. Aly ◽  
Mahmoud M. Mostafa

AbstractThe dimensions of many water streams, which satisfy proper hydraulic conditions, may not be compatible with the designed dimensions of an irrigation work that needs to be constructed in some locations. The design requirements of such irrigation works may involve a contraction in the channel width in the required location. This contraction, of course, affects different flow properties and the scour hole formed downstream of these structures. Therefore, the present experimental study aims to investigate the effect of the transition angle and the contraction on the flow properties and on the scour phenomenon downstream water structures. Through 460 experimental runs, carried out on 20 experimental models, the study proved that, for an efficient hydraulic performance and economic design, the best transition angle (θ) for the approaches of water structures is 30° with a relative contracted width ratio (r = b/B) not less than 0.6.


1994 ◽  
Vol 31 (10) ◽  
pp. 1043-1052 ◽  
Author(s):  
Yoshiyuki KATAOKA ◽  
Tadashi FUJII ◽  
Michio MURASE ◽  
Kenji TOMINAGA

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