Laboratory investigation on wave transmission through two rows of perforated hollow piles

Rao, Subba; Rao, N. B. S.; Sathyanarayana, V.S

doi:10.1016/s0029-8018(98)00021-3

Cited by 30 publications

(26 citation statements)

References 7 publications

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“…When two rows are closer, eddies formed around the rows and interfered increasingly, reducing turbulence between the rows (Rao, Rao, and Sathyanarayana, 1999). By contrast, for wider first spacing in d 1 /D for two rows and wider spacing in W/W 1 for three rows, eddies fully formed around each row, inducing more turbulence and resulting in a larger energy loss.…”

Section: Energy Loss Coefficientmentioning

confidence: 98%

“…Because Rao, Rao, and Sathyanarayana (1999) showed that wave attenuation is significantly affected by the addition of a second row, the experiments preferably employed three rows of independent vertical caisson piles and arranged them in various ways. Figure 2 is a detailed sketch of the arrangement of a caisson-pile group used as a permeable breakwater and a photo of the breakwater installed in the wave flume.…”

Section: The Breakwater Modelmentioning

confidence: 99%

“…The governing physical variables in the two tables can be converted into dimensionless variables by the dimensional analysis of Buckingham's -theorem (Rao, Rao, and Sathyanarayana, 1999), resulting in five significant dimensionless variables: In addition, the term W/gT can be rewritten as 2W/gT 2 2 s s or W/L 0,s , where L 0,s is the significant wavelength obtained using the dispersion relation in deep water. Hence, the three dimensionless hydraulic coefficients can be expressed using the five dimensionless variables in the form…”

Section: Physical Parameters For Hydraulic Characteristicsmentioning

confidence: 99%

“…Rao, Rao, and Sathyanarayana (1999) investigated wave transmission through two rows of piles and showed that the transmission coefficient (K t ) is considerably influenced by the addition of a second row. They also revealed that K t decreases with the (relatively clear) spacing between piles in a row.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of the Hydraulic Performance of Caisson-Pile Breakwaters

Yoo

Kim²,

Kim

et al. 2010

Journal of Coastal Research

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Porous breakwaters using a caisson-pile group can increase the resistance of the vertical coastal structures in harbors to external heavy impacts, and also help facilitate the exchange of water. This article presents experimental results for the hydraulic performance of independent caisson-pile type breakwaters having three rows of vertical piles, both evenly and unevenly spaced between rows. Compared with even spacing, uneven, sparser spacing tends to have lower wave reflections and higher energy loss coefficients. Wave transmission, by contrast, appears not to be considerably influenced by spacing pattern. The transmission coefficient increases with wave steepness (S 0,s ) and decreases with the ratio of the (total) width of the three pile rows to the wavelength (W/L 0, s ). ADDITIONAL INDEX WORDS:Uneven spacing of vertical piles, wave reflection coefficient, wave transmission coefficient, energy loss coefficient.

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Section: Energy Loss Coefficientmentioning

confidence: 98%

Section: The Breakwater Modelmentioning

confidence: 99%

Section: Physical Parameters For Hydraulic Characteristicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of the Hydraulic Performance of Caisson-Pile Breakwaters

Yoo

Kim²,

Kim

et al. 2010

Journal of Coastal Research

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“…The performance of these barriers mainly depends on the geometry and size of the piles, the pile spacing and their distribution. The study of wave interaction on the barriers with rectangular piles was studied by Huang (2007), Heikal et al (2007) and Koraim (2007); whilst those with circular piles was investigated by Subba Rao et al (1999), Yagci et al (2006), Koraim (2007) and Heikal et al (2007). A comparison of results by Koraim (2007) showed that the square pile breakwater was more efficient than the circular piles in wave attenuation by 5% -15%, and the efficiency increased with a decrease in pile spacing and an increase in the span width.…”

Section: (B) Pile Breakwatersmentioning

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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Hydrodynamic Performance of Pile Supported Breakwaters—A Review

2019

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Laboratory investigation on wave transmission through two rows of perforated hollow piles

Cited by 30 publications

References 7 publications

Experimental Investigation of the Hydraulic Performance of Caisson-Pile Breakwaters

Experimental Investigation of the Hydraulic Performance of Caisson-Pile Breakwaters

Performance Analysis of Composite Semicircular Breakwaters of Different Configurations and Porosities

Hydrodynamic Performance of Pile Supported Breakwaters—A Review

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