Experimental Study on the Wave Attenuation of Porous Pipe Breakwaters

2011 ◽  
Vol 105-107 ◽  
pp. 1349-1352
Author(s):  
Ruey Syan Shih

The dissipation of porous perpendicular pipe breakwaters are studied experientially in this study, the investigations on wave transmission of the porous pipe breakwaters are carried out in the laboratory with different wave conditions and various combinations of pipe diameter and length. The wave energy is mainly dissipated due to the drag and interception of the resultant motion by the pipe breakwaters, the reflectivity of such effect are thus discussed by the evaluation of partly reflected and transmitted ratio, and consequently the performance of the pipe breakwater for predicting wave transmission coefficient is investigated. Experimental results revealed that the attenuation is much effective with the decreasing of pipe diameter than increasing of the length.

2020 ◽  
Vol 82 (3) ◽  
Author(s):  
‘Izzat Na’im Ibrahim ◽  
Mohd Shahrizal Ab Razak ◽  
Badronissa Yusof ◽  
Safari Mat Desa

The main objective of this paper is to determine the wave transmission coefficient of an improved submerged breakwater called WABCORE. The objective is further explored to assess the effect of various parameters such as wave steepness, Hi/L, relative freeboard, R/d, and relative width of the top crest, B/L on wave transmission coefficient, KT. In general, as wave steepness increases, the wave transmissions decrease. Moreover wave transmission increases as relative freeboard increases. This is due to the fact that higher relative freeboard contains greater wave energy and hard to dissipate. As B/L increases, KT decreases. The effect of relative top crest width is insignificant as the freeboard increases. The transmission coefficient, KT derived from this study can be equated as  , valid for certain ranges. This study concludes that WABCORE is capable to dissipate wave energy.


1993 ◽  
Vol 8 (9) ◽  
pp. 2344-2353 ◽  
Author(s):  
J-M. Berthelot ◽  
Souda M. Ben ◽  
J.L. Robert

The experimental study of wave attenuation in concrete has been achieved in the case of the propagation of plane waves in concrete rods. Different mortars and concretes have been investigated. A transmitter transducer coupled to one of the ends of the concrete rod generates the propagation of a plane wave in the rod. The receiver transducer, similar to the previous one, is coupled to the other end of the rod. The experimental results lead to an analytical expression for wave attenuation as function of the concrete composition, the propagation distance, and the wave frequency.


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.


2019 ◽  
Vol 139 ◽  
pp. 538-550 ◽  
Author(s):  
Shaohui Yang ◽  
Hongzhou He ◽  
Hu Chen ◽  
Yongqing Wang ◽  
Hui Li ◽  
...  

1972 ◽  
Vol 55 (1) ◽  
pp. 149-161 ◽  
Author(s):  
D. C. Guiney ◽  
B. J. Noye ◽  
E. O. Tuck

The water-wave transmission coefficient for a small slit in a thick vertical barrier is obtained theoretically and verified both experimentally and by comparison with an exact theory for the case of zero thickness. Similar shallow-water results are presented.


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