Wave reflection by a submerged cycloidal breakwater in presence of a beach with different depth profiles

Breakwater is used to break the wave energy that travels towards the beach. Part of the wave energy will be destroyed, transmitted, or reflected. The shape of breakwater affects the ability to break the wave energy. There are no researchers who have compared the effect of the shape of the breakwater structure on wave energy transmitted and reflected. This study aims to simulate the transmission coefficient (Kt) and reflection coefficient (Kr) of the breakwater in various forms. Physical models with a 1:100 scale model is used. A flap-type wave generator in a wave flume is used to generate the wave. Waves regularly move in one direction passed the model. The results showed an effect of the shape of the breakwater structure on Kt and Kr. By increasing the wave steepness (Hi/L), Kt's value will increase in the upright structure and decrease in the sloping structure. At the same time, the value of Kr tends to decrease when the wave steepness increases. The value of Kt is relatively smaller in upright structures than in sloping structures. By adding porosity to the structure, the Kt value will increase, followed by Kr's reduction. By increasing the crest B's width, Kt appears to increase, but the crest width does not significantly affect Kr. Kt and Kr are significantly smaller if the breakwater structure is inclined towards the sea or inverted trapezium. This type of breakwater has never been encountered in the field before.

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“… Calculate the reflection coefficient (Kr) and the transmission coefficient (Kt) using equations ( 5) and (6).…”

Section: Methodsmentioning

confidence: 99%

Physical Model Simulation: Influences the Shape of Breakwater Structures on the Coefficient of Transmission and Reflection

Pujianiki¹,

Dayanti²

2021

Int. J. Adv. Sci. Eng. Inf. Technol.

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Modeling Ocean Swell and Overtopping Waves: Understanding Wave Shoaling with Varying Seafloor Topographies

Wong,

Chow

2024

JMSE

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One risk posed by hurricanes and typhoons is local inundation as ocean swell and storm surge bring a tremendous amount of energy and water flux to the shore. Numerical wave tanks are developed to understand the dynamics computationally. The three-dimensional equations of motion are solved by the software ‘Open Field Operation And Manipulation’ v2206. The ‘Large Eddy Simulation’ scheme is adopted as the turbulence model. A fifth-order Stokes wave is taken as the inlet condition. Breaking, ‘run-up’, and overtopping waves are studied for concave, convex, and straight-line seafloors for a fixed ocean depth. For small angles of inclination (<10°), a convex seafloor displays wave breaking sooner than a straight-line one and thus actually delivers a smaller volume flux to the shore. Physically, a convex floor exhibits a greater rate of depth reduction (on first encounter with the sloping seafloor) than a straight-line one. Long waves with a speed proportional to the square root of the depth thus experience a larger deceleration. Nonlinear (or ‘piling up’) effects occur earlier than in the straight-line case. All these scenarios and reasoning are reversed for a concave seafloor. For large angles of inclination (>30°), impingement, reflection, and deflection are the relevant processes. Empirical dependence for the setup and swash values for a convex seafloor is established. The reflection coefficient for waves reflected from the seafloor is explored through Fourier analysis, and a set of empirical formulas is developed for various seafloor topographies. Understanding these dynamical factors will help facilitate the more efficient designing and construction of coastal defense mechanisms against severe weather.

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Wave reflection by a submerged cycloidal breakwater in presence of a beach with different depth profiles

Cited by 2 publications

References 24 publications

Physical Model Simulation: Influences the Shape of Breakwater Structures on the Coefficient of Transmission and Reflection

Physical Model Simulation: Influences the Shape of Breakwater Structures on the Coefficient of Transmission and Reflection

Modeling Ocean Swell and Overtopping Waves: Understanding Wave Shoaling with Varying Seafloor Topographies

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