Wave Transmission over the Low-Crested Sand Container Breakwaters

2015 ◽  
Vol 802 ◽  
pp. 57-62
Author(s):  
Hee Min Teh
Keyword(s):  
Shallow Water ◽  
Transmission Coefficient ◽  
Water Depth ◽  
Wave Transmission ◽  
Experimental Result ◽  
Regular Waves ◽  
Wave Flume ◽  
Test Models ◽  
Wave Transmission Coefficient ◽  
Transmission Ability

Breakwaters made of sand container is one of the most economical options for wave protection at coastal areas. These breakwaters have been adopted with mixed success at several locations in Malaysia. Nevertheless, the performance of these structure has not been properly studied and documented to date. This study is undertaken to study the wave transmission ability of the submerged sand container breakwater with respect to its width and height as well as the water depth. A number of experiments have been conducted in a wave flume to quantify the wave transmission coefficient of the test models of different layouts when exposed to regular waves. The experimental result has shown that the breakwater is effective in arresting the shorter period waves, particularly in shallow water. The height of the breakwater has to be increased in order to arrest the longer period waves.

Transmission of water waves through small apertures

1972 ◽  
Vol 55 (1) ◽  
pp. 149-161 ◽  
Author(s):  
D. C. Guiney ◽  
B. J. Noye ◽  
E. O. Tuck
Keyword(s):  
Shallow Water ◽  
Transmission Coefficient ◽  
Water Waves ◽  
Water Wave ◽  
Wave Transmission ◽  
Exact Theory ◽  
Vertical Barrier ◽  
Wave Transmission Coefficient

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.

Optimization of Hydraulic Efficiency of a Free Surface Semicircular Breakwater Using Wave Screens

2015 ◽  
Author(s):  
Hee Min Teh ◽  
Vengatesan Venugopal
Keyword(s):  
Free Surface ◽  
Wave Climate ◽  
Wave Transmission ◽  
Hydrodynamic Performance ◽  
Wave Transformation ◽  
Random Waves ◽  
Wave Flume ◽  
Wave Measurements ◽  
Test Models ◽  
Semicircular Breakwater

A free surface semicircular breakwater (SCB) with rectangular perforations has been developed to serve as a wave defence structure. Hydrodynamic performance of the breakwaters of various perforations has been thoroughly investigated through wave measurements in a wave flume under random waves. The SCBs were experimentally confirmed to be good anti-reflection wave structures; however, the level of wave transmission at the leeside of the SCBs was rather high particularly when immersed in limited depth and confronted by waves of longer period. This study aims at optimizing the hydraulic characteristics of the SCB by extending its draft by means of wave screens. Three test configurations have been identified in this study, namely (1) the SCB with front screen, (2) the SCB with rear screen, and (3) the SCB with double screens. For each wave screen, three porosities (i.e. 25, 40 and 50%) have been considered in the experiments. The models of shallow immersion depths have been tested in random waves of different characteristics in a wave flume. Wave transformation at different locations upstream and downstream of the test models has been recorded by wave probes. The hydraulic performance of the breakwater are quantified by the coefficients of wave transmission, reflection and energy dissipation, and the wave climate in the vicinity of the breakwater are presented in the form of a ratio relative to the incident wave height. The optimum design of SCB supplemented by truncated wave screen(s) is proposed at the end of the study.

scholarly journals TRANSMISSION OF REGULAR WAVES PAST FLOATING PLATES

1974 ◽  
Vol 1 (14) ◽  
pp. 112
Author(s):  
Uygur Sendil ◽  
W.H. Graf
Keyword(s):  
Water Depth ◽  
Wave Length ◽  
Wave Theory ◽  
Finite Amplitude ◽  
Linear Wave ◽  
Regular Waves ◽  
Transmission Coefficients ◽  
Wave Flume ◽  
Wave Heights ◽  
Incident Waves

Theoretical solutions for the transmission beyond and reflection of waves from fixed and floating plates are based upon linear wave theory, as put forth by John (1949), and Stoker (1957), according to which the flow is irrotational, the fluid is incompressible and frictionless, and the waves are of small amplitude. The resulting theoretical relations are rather complicated, and furthermore, it is assumed that the water depth is very small in comparison to the wave length. Wave transmissions beyond floating horizontal plates are studied in a laboratory wave flume. Regular (harmonic) waves of different heights and periods are generated. The experiments are carried out over a range of wave heights from 0.21 to 8.17 cm (0.007 to 0.268 ft), and wave periods from 0.60 to 4.00 seconds in water depth of 15.2, 30.5, and 45.7 cm (0.5, 1.0 and 1.5 ft). Floating plates of 61, 91 and 122 cm (2, 3 and 4 ft) long were used. From the analyses of regular waves it was found that: (1) the transmission coefficients, H /H , obtained from the experiments are usually less than those obtained from the theory. This is due to the energy dissipation by the plate, which is not considered in the theory. (2) John's (1949) theory predicts the transmission coefficients, H /H , reasonably well for a floating plywood plate, moored to the bottom and under the action of non-breaking incident waves of finite amplitude. (3) a floating plate is less effective in damping the incident waves than a fixed plate of the same length.

scholarly journals Wave Energy Harnessing in Shallow Water through Oscillating Bodies

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2730 ◽  
Author(s):  
Marco Negri ◽  
Stefano Malavasi
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Wave Energy ◽  
Multibody System ◽  
Physical Models ◽  
Width Ratio ◽  
Wave Flume ◽  
Capture Width Ratio ◽  
Single Body ◽  
Two Systems

This paper deals with wave energy conversion in shallow water, analyzing the performance of two different oscillating-body systems. The first one is a heaving float, which is a system known in the literature. The second one is obtained by coupling the heaving float with a surging paddle. In order to check the different behaviors of the multibody system and the single-body heaving float, physical models of the two systems have been tested in a wave flume, by placing them at various water depths along a sloping bottom. The systems have been tested with monochromatic waves. For each water depth, several tests have been performed varying the geometrical and mechanical parameters of the two systems, in order to find their best configurations. It has been found that the multibody system is more energetic when the float and the paddle are close to each other. Capture width ratio has been found to significantly vary with water depth for both systems: in particular, capture width ratio of the heaving float (also within the multibody system) increases as water depth increases, while capture width ratio of the paddle (within the multibody system) increases as water depth decreases. At the end, the capture width ratio of the multibody system is almost always higher than that of the heaving float, and it increases as water depth increases on average; however, the multibody advantage over single body is significant for water depth less than the characteristic dimension of the system, and decreases as water depth increases.

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