Hydrodynamic Characteristics of Submerged Impermeable and Seaside Perforated Semicircular Breakwaters

doi:10.1115/OMAE2002-28188

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Hydrodynamic Characteristics of Submerged Impermeable and Seaside Perforated Semicircular Breakwaters

Proceedings Article•DOI•

Hydrodynamic Characteristics of Submerged Impermeable and Seaside Perforated Semicircular Breakwaters

G. Dhinakaran¹, Vallam Sundar¹, R. Sundaravadivelu¹, K.-U. Graw²•Institutions (2)

Indian Institute of Technology Madras¹, Leipzig University²

01 Jan 2002-pp 401-408

TL;DR: In this article, the reflection and transmission characteristics of perforated semicircular breakwater as a function of scattering parameter, ka is reported and the results on the above stated variables are compared with the results for an impermeable SBW.

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Abstract: The semicircular breakwater (SBW) is one of the varieties of breakwaters, which has emerged recently. The world’s first semicircular breakwater has been constructed at Miyazaki port in Japan. The dynamic pressures due to regular waves exerted on a SBW with 7% of its seaside surface area with perforations were measured. The variations of dimensionless pressures for three different water depth (hw ) to total height of the model (ht ), ratios are presented and discussed in this paper. In addition, the reflection and transmission characteristics of the perforated SBW as a function of scattering parameter, ka is reported. The results on the above stated variables for a seaside perforated SBW are compared with the results for an impermeable SBW.Copyright © 2002 by ASME

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Journal Article•DOI•

Performance Assessment of a Semi-Circular Breakwater through CFD Modelling

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Ana Gomes, José L. S. Pinho, Tiago Valente, José Simão Antunes do Carmo, Arkal V. Hegde - Show less +1 more

23 Mar 2020-Journal of Marine Science and Engineering

TL;DR: In this paper, the authors presented the results of the application of a computational fluid dynamics (CFD) tool to study the stability of a perforated semicircular breakwater, based on a rubble mound foundation.

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Abstract: Coastal defence works, such as breakwaters, are structures that aim to support the action of waves and dissipate their energy. Therefore, they provide conditions for stabilizing the coast, protecting ports, beaches and other coastal infrastructures and ecosystems. Semicircular breakwaters have been applied in different locations around the world due to their aesthetic advantages and high structural performance. Marine structures are subject to hydrodynamic actions normally estimated through physical models. However, these models are complex to implement, involving high costs and long experimental procedures. Thus, alternative methodologies for studying the hydrodynamic performance of these structures are of great use. This work presents the results of the application of a computational fluid dynamics (CFD) tool to study the stability of a perforated semicircular breakwater, based on a rubble mound foundation. The model was validated against experimental results of the critical weight necessary to resist sliding, taking into account the effects of water depth and different characteristics of the waves. A comparison is made between the perforated and the non-perforated solution in terms of the breakwater’s performance to dissipate wave energy. Dissipation conditions of this energy, in the exposed face, are also evaluated in detail, in order to assess the potential of this structure as a biological refuge for marine species. Both solutions show similar performance in terms of results obtained for the wave reflectivity coefficient. The turbulence dissipation on the exposed face of the perforated breakwater is limited to a region of restricted extension around it, which is advantageous in terms of the passage of species into the breakwater.

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20 citations

Journal Article•DOI•

Review of the research on emerged and submerged semicircular breakwaters

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G. Dhinakaran¹, Vallam Sundar², R. Sundaravadivelu²•Institutions (2)

Shanmugha Arts, Science, Technology & Research Academy¹, Indian Institute of Technology Madras²

02 Jul 2012

TL;DR: In this article, the hydrodynamic characteristics of semicircular breakwaters were studied in Japan and the People's Republic of China, particularly in the case of breakwaters in the Japanese archipelago.

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Abstract: Scientists and researchers are currently focusing considerable attention on the hydrodynamic characteristics of semicircular breakwaters worldwide, particularly in Japan and the People’s Republic o...

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9 citations

Journal Article•DOI•

Run-up, run-down and reflection characteristics of semicircular breakwater for varying seaside perforations

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Arkal Vittal Hegde¹, Subba Rao¹, Kiran Kumar¹•Institutions (1)

National Institute of Technology, Karnataka¹

30 Oct 2012-ISH Journal of Hydraulic Engineering

TL;DR: In this article, physical studies conducted on seaside-perforated semicircular breakwater models to evaluate the wave run-up, wave rundown, and reflection coefficient for various wave heights (H), wave periods (T), water depths (d), incident wave steepness (H i/gT 2), depth parameter (d/ gT ǫ 2), and relative spacing S/D (Sǫ = c/c spacing of perforations, Dǫ=

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Abstract: Breakwaters are mainly used for the purpose of withstanding and dissipating the dynamic energy of ocean waves and thereby provide tranquillity conditions on the lee side. Semicircular breakwaters are being used increasingly around the globe because of their great advantages. The paper explains physical studies conducted on seaside-perforated semicircular breakwater models to evaluate the wave run-up, wave run-down, and reflection coefficient for various wave heights (H), wave periods (T), water depths (d), incident wave steepness (H i/gT 2), depth parameter (d/gT 2), and relative spacing S/D (S = c/c spacing of perforations, D = diameter of perforations) on the seaside. It is observed that as the incident wave steepness increases, there is a decrease in the reflection coefficient (K r), and relative run-down (R d/H i) but increase in relative run-up (R u/H i). As the S/D ratio decreased (percentage of perforations increased), there was drop in the reflection coefficient, relative run-up, and relative run...

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4 citations

Journal Article•DOI•

Hydrodynamic performance characteristics of semicircular breakwater—wave run-up and run-down

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Arkal Vittal Hegde M.Ish¹, C. Ganesh¹, Vishal Kumar¹•Institutions (1)

National Institute of Technology, Karnataka¹

01 Jan 2010-ISH Journal of Hydraulic Engineering

TL;DR: In this paper, the wave run-up and run-down values on a semicircular breakwater model for various incident wave heights H, wave periods T, water depths d and spacing (S to diameter (D) ratios of perforations (S/D) were analyzed.

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Abstract: Breakwaters are structures protecting a shore area, harbor, anchorage, or a basin from the fury of ocean waves. They create calm waters and give protection for safe mooring, operating and handling of ships, and provide protection to harbor facilities. Semicircular breakwaters are becoming increasingly popular these days, as they have high stability against the action of waves. The paper explains the physical model studies to evaluate the wave run-up (Rd/Hi) and wave run-down (Rd/Hi) on semicircular breakwater model for various incident wave heights H, wave periods T, water depths d and spacing (S) to diameter (D) ratios of perforations (S/D). It is found that relative wave run-up increases with the increase in wave steepness (Hi/gT2) and relative run-down decreases with the increase in wave steepness. Relative wave run-up and wave run-down values increase with the increase in depth parameter (d/gT2). The relative run-up and run-down values decrease with increasing perforations (decreasing S/D val...

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4 citations

Journal Article•DOI•

Transmission performance of submerged semicircular breakwaters for different radii and submergence ratios

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Arkal Vittal Hegde, S.M. Naseeb¹•Institutions (1)

National Institute of Technology, Karnataka¹

01 Sep 2014-The International Journal of Ocean and Climate Systems

TL;DR: In this article, the transmission characteristics of scaled down semicircular breakwater (SBW) physical models of different radii (R) for different submergence ratios (d/hc), where d is the depth of water and hc is the height of the breakwater crest from the sea bed, were evaluated.

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Abstract: The paper presents the results of a series of laboratory experiments that were conducted in a 2D monochromatic wave flume of the department to evaluate the transmission characteristics of scaled down semicircular breakwater (SBW) physical models of different radii (R) for different submergence ratios (d/hc), where d is the depth of water and hc is the height of the breakwater crest from the sea bed. The radii of the breakwater models studied were 20 cm, 22.5 cm, 25 cm, and 27.5 cm and d/hc values used varied from 1.067 to 1.667. The wave climate along the Mangalore coast of India was used for arriving at the various wave parameters. Incident wave heights (Hi) used varied from 3 to 18 cm, wave periods (T) ranged from 1.2 s to 2.2 s with water depths (d) of 40 cm, 45 cm and 50 cm. The data collected was analyzed by plotting the non-dimensional graphs depicting the variation of transmission coefficient Kt (Kt = Ht/Hi, where Ht = transmitted wave height) with wave steepness Hi/gT2 for different R/Hi and d/hc ...

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2 citations

Cites result from "Hydrodynamic Characteristics of Sub..."

...Dhinakaran et al. (2002) carried out detailed investigation on the reflection and transmission characteristics and hydrodynamic pressures due to the action of regular waves, on a submerged seaside perforated semicircular breakwater model with 7% perforations. The ratio of the height of the rubble to the total height of the breakwater (hr/ht) is kept constant as 0.18. The water depth to the total height of the model (hw/ht) was varied as 1.0, 1.2 and 1.4. The results have been compared with that of an impermeable semicircular model. Based on the detailed experimental investigations conducted, the following conclusions are arrived. The Kr is found to decrease with increase in water depth and is higher for submerged seaside perforated semicircular breakwater model with 7% perforations It is observed that, the seaside perforated semicircular breakwater dissipates more energy due to the provision of perforations and hence reflects lesser amount of energy. Subba Rao and Sundar (2002) have done experimental work on hydrodynamic pressures and forces on Quadrant front face pile supported breakwater....
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...Dhinakaran et al. (2002) carried out detailed investigation on the reflection and transmission characteristics and hydrodynamic pressures due to the action of regular waves, on a submerged seaside perforated semicircular breakwater model with 7% perforations. The ratio of the height of the rubble to the total height of the breakwater (hr/ht) is kept constant as 0.18. The water depth to the total height of the model (hw/ht) was varied as 1.0, 1.2 and 1.4. The results have been compared with that of an impermeable semicircular model. Based on the detailed experimental investigations conducted, the following conclusions are arrived. The Kr is found to decrease with increase in water depth and is higher for submerged seaside perforated semicircular breakwater model with 7% perforations It is observed that, the seaside perforated semicircular breakwater dissipates more energy due to the provision of perforations and hence reflects lesser amount of energy. Subba Rao and Sundar (2002) have done experimental work on hydrodynamic pressures and forces on Quadrant front face pile supported breakwater. Quadrant front face pile supported breakwater is a combination of semicircular and closely spaced pile breakwaters, which couples the advantages of these two types. This type of structure consists of two parts. The bottom portion consists of closely spaced piles and the top portion consists of a quadrant solid front face on the seaside. The leeward side of the top portion with a vertical face would facilitate the berthing of vessels. An experimental investigation on this breakwater model in a wave flume is carried out for three water depths. For each water depth, three different spacing’s between the piles were adopted for the investigation. The dynamic pressures exerted along the quadrant front face due to regular waves were measured. The variation of dimensionless pressures with respect to scattering parameter for different gap ratio (spacing between the piles/diameter of pile) and for relative pile depth (water depth/pile height) are presented and discussed. In addition, the dimensionless total forces exerted on the breakwater model as well as its reflection characteristics as a function of scattering parameter is reported. Kr increases with increase in ka, from about 0.25 to 0.50, 0.25 to 0.70 and 0.20 to 0.85 for d/h=1.45, 1.63 and 1.81, respectively. Further, the rate of increase is found to be higher for higher d/h. A superposition of the lines of best fit reveals that Kr is lesser for lesser water depth (d/h=1.45) and Kt decreases with increase in ka. The loss coefficient Kl, was obtained from the evaluated Kr and Kt as Kl = √1− (Kr(2) + Kt(2)). For lesser water depth, Kl increases with increase in ka, whereas for higher water depths, Kl decreases with increase in ka. Chang-gen et al. (2004) developed a vertical 2D numerical wave model based on unsteady Reynolds equations....
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...Dhinakaran et al. (2002) carried out detailed investigation on the reflection and transmission characteristics and hydrodynamic pressures due to the action of regular waves, on a submerged seaside perforated semicircular breakwater model with 7% perforations....
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References

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Journal Article•DOI•

The Measurement of Incident and Reflected Spectra Using a Least squares Method

[...]

Etienne Mansard¹, E.R. Funke¹•Institutions (1)

National Research Council¹

29 Jan 1980

TL;DR: In this article, a least square method to separate the incident and reflected spectra from the measured coexisting spectra is presented, which requires a simultaneous measurement of the waves at three positions in the flume which are in reasonable proximity to each other and are on a line parallel to the direction of wave propagation.

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Abstract: A least squares method to separate the incident and reflected spectra from the measured co-existing spectra is presented. This method requires a simultaneous measurement of the waves at three positions in the flume which are in reasonable proximity to each other and are on a line parallel to the direction of wave propagation. Experimental investigations have shown that there is good agreement between the incident spectra calculated by the least squares method and the incident spectra measured concurrently in a side channel.

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712 citations

Journal Article•DOI•

New wave pressure formulae for composite breakwaters

[...]

Yoshimi Goda¹•Institutions (1)

Ontario Ministry of Transportation¹

29 Jan 1974

TL;DR: In this paper, a wave pressure formulae for the whole ranges of wave action from non-breaking to post-breaking waves with smooth transition between them is proposed. But the proposed wave pressure is not suitable for the case of non-sliding breakwaters.

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Abstract: A proposal is made for new wave pressure formulae, which can be applied for the whole ranges of wave action from nonbreaking to postbreaking waves with smooth transition between them. The design wave height is specified as the maximum wave height possible at the site of breakwater. The new formulae as well as the existing formulae of Hiroi, Sainflou, and Minikin have been calibrated with the cases of 21 slidings and 13 nonslidings of the upright sections of prototype breakwaters. The calibration establishes that the new formulae are the most accurate ones.

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230 citations

Journal Article•DOI•

Numerical Simulation of Random Wave Forces Near the Free Surface

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Michael Isaacson¹, K. Subbiah¹•Institutions (1)

University of British Columbia¹

01 Feb 1991-Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme

19 citations

Standing wave pressures due to regular and random waves on a vertical wall

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Mallayachari, Sundar

01 Jan 1995

TL;DR: In this paper, the standing wave pressures due to laboratory-generated regular and random waves exerted on a vertical wall were measured in a wave flume, and the measured pressures were compared with results obtained using linear theory and third-order solution.

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Abstract: The standing wave pressures due to laboratory-generated regular and random waves exerted on a vertical wall were measured in a wave flume. The standing wave pressures were measured at four relative depths of submergence on the test model. The regular wave test conditions ranged from intermediate to deep water conditions. The measured pressures due to regular waves were compared with results obtained using linear theory and third-order solution. In the case of random wave tests, the dynamic pressures due to the time histories of water surface elevation following the spectral characteristics of Pierson-Moskowitz and Bretschneider spectra were measured. These pressures are compared with simulated pressures obtained through the linear filter technique of Reid. The variation of pressure spectra along the depth are presented. In addition, comparison of spectral parameters, ie zeroth moment, spectral width parameter and narrowness parameter of measured and simulated pressure spectra, are reported and discussed. The behaviour of the coherence function between the wave elevation on the wall and the corresponding pressures is also discussed.

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18 citations

Journal Article•DOI•

Standing wave pressures due to regular and random waves on a vertical wall

[...]

V. Mallayachari¹, Vallam Sundar¹•Institutions (1)

Indian Institute of Technology Madras¹

01 Nov 1995-Ocean Engineering

TL;DR: In this article, the standing wave pressures due to laboratory-generated regular and random waves exerted on a vertical wall were measured in a wave flume, at four relative depths of submergence on the test model.

...read moreread less

Abstract: The standing wave pressures due to laboratory-generated regular and random waves exerted on a vertical wall were measured in a wave flume. The standing wave pressures were measured at four relative depths of submergence on the test model. The regular wave test conditions ranged from intermediate to deep water conditions. The measured pressures due to regular waves were compared with results obtained using linear theory and third-order solution. In the case of random wave tests, the dynamic pressures due to the time histories of water surface elevation following the spectral characteristics of Pierson-Moskowitz and Bretschneider spectra were measured. These pressures are compared with simulated pressures obtained through the linear filter technique of Reid. The variation of pressure spectra along the depth are presented. In addition, comparison of spectral parameters, i.e. zeroth moment, spectral width parameter and narrowness parameter of measured and simulated pressure spectra, are reported and discussed. The behaviour of the coherence function between the wave elevation on the wall and the corresponding pressures is also discussed.

...read moreread less

17 citations