Performance Analysis of a Semicircular Free Surface Breakwater

Teh, Hee Min; Venugopal, Vengatesan; Bruce, Tom

doi:10.1115/omae2011-49700

Cited by 7 publications

(6 citation statements)

References 12 publications

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“…32 Further, researches were carried out on pile-supported structures such as quadrant front-face pile-supported breakwater, 11 half-submerged pile-supported breakwater, 33 curved and vertical front face pile-supported breakwater 34–36 and pile-supported semi-circular breakwater. 37,38 A zigzag porous screen breakwater was proposed by Mani, 2 where a zigzag porous screen was suspended between two rows of staggered piles (Refer Figure 1(f)). L-shaped and C-shaped bars were attached to the pile breakwaters to a certain depth to provide a higher obstruction area at the surface level.…”

Section: Introductionmentioning

confidence: 99%

Investigation on innovative pile head breakwater for coastal protection

Sathyanarayana

Suvarna

Umesh

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part M:

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Coastal erosion is a global concern that has been augmenting due to the natural evolution of beaches, human activities and sea-level rise. One of the eco-friendly shore protection methods is to dissipate the wave energy by constructing offshore breakwaters. Conical pile head breakwater (CPHB) is one of the eco-friendly innovative offshore structures consisting of closely spaced piles with an enlarged cross-sectional area (conical pile head) in the vicinity of the free surface. In the present study, perforations are incorporated over the conical pile head to achieve higher efficiency by promoting energy dissipation. The influence of the perforations on the performance characteristics, namely wave transmission (Kt), wave reflection (Kr) and energy dissipation (Kd) of the perforated CPHB is comprehensively investigated through physical model studies. The effect of perforations and their distribution around the pile head (Pa), percentage of perforation (P) and size of perforations (S/D) on the wave attenuation characteristics are evaluated to arrive at an optimum configuration. The study is carried out under monochromatic waves of varying wave height (0.06–0.16 m) and wave period (1.4–2 s) at different depths of water (0.35, 0.40 and 0.45 m). A minimum Kt of 0.58 associated with Kr of 0.26 and Kd of 0.78 is obtained with an optimum configuration of Pa = 50%, P = 19.2% and S/D = 0.25. The Kt of the proposed CPHB is about 19 to 35% lesser than that of the perforated hollow pile breakwater under matching test conditions. Overall, providing the perforations is found to be effective in enhancing the wave attenuation capability by up to 12.4%. Further, empirical equations are formulated and validated with the experimental data. The empirical equations estimate the Kt and Kr values accurately with a high coefficient of determination ( R2 ≥ 0.90).

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Section: Introductionmentioning

confidence: 99%

Investigation on innovative pile head breakwater for coastal protection

Sathyanarayana

Suvarna

Umesh

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part M:

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“…The results trend shows that all the k t decrease with increasing h/L. Moreover, the present model gives smaller transmission values than (Suh et al, 2006) and (Teh et al, 2011) and larger values compared with others.…”

Section: Comparison With Previous Studiesmentioning

confidence: 49%

“…Moreover, the MPR model and Flow-3D predicts the transmission coefficient with acceptable degree of accuracy. Figure 10presents the hydrodynamic performance of the different semi-immersed models, investigated by other published work of (Teh et al, 2011), (Suh et al, 2006), (Sundar and Subba Rao, 2002), (Koutandos et al, 2005), (He and Huang, 2014), (Duclos et al, 2004) and (Neelamani and Rajendran, 2002).The performance of the different models (k t ) is plotted as a function of h/L. The characteristics of these experimental studies are shown in Table (1).…”

Section: Comparison With Previous Studiesmentioning

confidence: 99%

Wave Interaction Of Partially Immersed Semicircular Breakwater Suspended On Piles Using Flow-3D

Abozaid¹,

Mahmod²,

Koraim³

et al. 2018

Progress in Canadian Mechanical Engineering

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This paper experimentally investigates the wave transmission through partially immersed semicircular breakwater suspended on two rows of circular piles. Different wave and structure parameters have been investigated such as; incident wave height, wave length, wave period, breakwater draft and the clear gap between the supporting piles. Multiple Polynomial Regression (MPR) model is used to develop an empirical equation to calculate the transmission coefficient (k t) as a representative of the transmitted wave energy. In addition, a Flow-3D numerical study is carried out to simulate the transmitted wave hydrodynamics and verified against the experimental results. The numerical analysis shows good agreement with experimental results with an acceptable value of NRMSE. The results show that the transmission coefficient (k t) decreases by about 31% with increasing the relative wave length from 0.12 to 0.22 and wave steepness from 0.006 to 0.021. Also, the transmitted coefficient (k t) decreases by about 25% with increasing the relative immersion depths from 0.25m to 0.5m and increases by about 16% for increasing of pile porosity value from 0.5 to 0.83 respectively.

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“…The radius and breakwater length perpendicular to the wave direction for the model were 0.25 m and 0.395 m, respectively. Further details of the test model were presented by Teh et al (2011;2012). A 300-mm screen of various porosities (i.e.…”

Section: Methodsmentioning

confidence: 99%

“…The transmitted waves were measured by probe WP6, which was located at a distance 2.5 m from the leeward wall of the model. The horizontal wave forces acting on the SCB model were measured by two load cells (LC1 and LC2) attached at both ends of the model at the crest through a specially designed mounting frame, in which the details are described by Teh et al (2011Teh et al ( , 2012. For the wave screens, the total horizontal wave force on the respective structures was measured by S-type load cells of IP68 supplied by Ningbo Xinlan Electric Appliances Co. Ltd, China.…”

Section: Methodsmentioning

confidence: 99%

Performance Analysis of Composite Semicircular Breakwaters of Different Configurations and Porosities

Teh¹,

Venugopal²,

Bruce³

2012

Int. Conf. Coastal. Eng.

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The perforated free surface semicircular breakwater developed by Teh et al. (2010) was experimentally proven to be an effective anti-reflection structure with high energy dissipation ability. However, the performance characteristics of the breakwater deteriorated with a decrease in the immersion depth and an increase in wavelength. To enhance the performance of the breakwater with limited immersion depth, wave screens of different configurations and porosities were introduced below the free surface semicircular caisson. The hydrodynamic characteristics of these composite breakwaters were investigated in irregular waves using physical modelling. Comparisons of the experimental results showed that the semicircular caisson with a double screen of 25% porosity was a better breakwater configuration compared to that with a single screen. The extension of wave screen was also found to be particularly helpful in attenuating longer waves.Keywords: free surface breakwater, semicircular breakwater, wave screen, wave transmission, wave reflection, energy dissipation, horizontal wave forces. INTRODUCTIONFree surface breakwaters, also known as open breakwaters, have generated a great deal of interest in the coastal and ocean engineering in recent years. They are essentially barriers located near the free surface where the energy flux is greatest. Such barriers do not extend over the whole water depth, permitting water circulation beneath the structure. These breakwaters could be installed on a group of piles. These structures control the height of the waves mainly by reflection and energy loss, and have been found to be most effective when used at locations where wave conditions are relatively mild.Teh et al. (2010) developed a perforated free surface semicircular breakwater (SCB) that was particularly suitable to be used in near-shore waters. Over the tested range, the SCB was an effective energy dissipater and a reasonable wave reflector. The experimental results indicated that the wave attenuation performance of the SCB model was somewhat less satisfactory at lower immersion depths, particularly when subjected to longer period waves, due to substantial transmission of waves underneath the structure. The wave transmission for the structure at lower immersion ranged from about 60% -98%, which is rather high for many coastal and marine related applications. Hence the aim of the present study is to reduce the transmission level by introducing wave screens that are directly attached underneath the SCB model. The hydrodynamic characteristics of the combined semicircular breakwater with screens of different configurations and porosities are investigated under irregular waves in a wave flume. The main purpose of the experimental exercise is to evaluate the effectiveness of such a composite breakwater in lower immersion depth.The present study aims to address the aforementioned problem by introducing a wave screen(s) of various porosities underneath the SCB. The hydrodynamic characteristics of the test models of different configura...

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Performance Analysis of a Semicircular Free Surface Breakwater

Cited by 7 publications

References 12 publications

Investigation on innovative pile head breakwater for coastal protection

Investigation on innovative pile head breakwater for coastal protection

Wave Interaction Of Partially Immersed Semicircular Breakwater Suspended On Piles Using Flow-3D

Performance Analysis of Composite Semicircular Breakwaters of Different Configurations and Porosities

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