• Journal of Industrial Technology
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• v.20 no.A
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• pp.139-148
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• 2000

A numerical model is represented to calculate the wave fields such as the reflected waves, the transmitted waves, and depth averaged velocities over submerged breakwaters for the normally incident wave trains of nonlinear monochromatic wave. The numerical model is correctly formulated by using both the finite amplitude shallow water equations with the effects of bottom friction and the explicit dissipative Lax-Wendroff finite difference scheme, also satisfactorily verified by comparison with the other results. The behaviors of reflected and transmitted waves with respect to geometric parameters of submerged breakwater such as the slope, crest depth, and crest width are numerically analyzed in this study. In particular, the reflection and transmission coefficients are quantitatively calculated as the function of geometric parameter of submerged breakwater. It is found that the crest depth among parameters related to practical design may be the most important parameter in designing the submerged breakwater. Therefore, the effective and economic performances of submerged breakwater should be depended on the determination of optimal crest depth.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.453-456
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• 2006

To examine the effect of shape and crest width variation of a permeable submerged breakwater on the wave energy dissipation, Two-Dimensional numerical model with Large Eddy Simulation, which is able to simulate directly WAve Structure Seabed interaction (hereafter, LES-WASS-2D) has been newly developed. A good agreement has been obtained by the comparison between the existing experimental results and LES-WASS-2D model's results for the permeable submerged breakwater. Moreover, based on the LES-WASS-2D model, the wave energy dissipation due to a permeable submerged breakwater are discussed for regular and irregular waves with relation to its crest width and shape.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.1
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• pp.23-32
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• 2011

Numerical analysis of hydrodynamic performance of a movable submerged breakwater was carried out as an eco-friendly marine structure for coastal and harbor protection. Using boundary elements method with two-dimensional frequency-domain reflection and transmission coefficients and wave forces acting on the submerged flat plate were calculated with various submerged depths and respective motion allowable modes. The movable breakwater was found to be more efficient in wave-blocking than the fixed structure. Variation of reflection coefficients was significantly influenced by vertical motion of the body.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.275-276
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• 2013

This analysis method is based on the wave pressure function with the continuity in the analytical region including fluid and porous structures. Wave profiles coming with oblique angle to permeable submerged breakwater on the porous seabed are computed numerically by using boundary element method. When compared with the existing results for the oblique incident wave, the results of this study show good agreement. The results indicate that wave profiles own high dependability regarding the change of oblique incident waves and permeable submerged breakwater on the porous seabed. Therefore, the analysis method of this study are estimated to be applied as an accurate numerical analysis referring to oblique incident waves and permeable submerged breakwater on the porous seabed in real sea environment.

• Ocean Systems Engineering
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• v.5 no.4
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• pp.319-329
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• 2015

Submerged breakwaters are used to prevent shore line erosion and sediment transportation. One of their advantages is low visual impact. In this paper, the effects of discontinuous submerged breakwaters over water surface elevation was numerically studied considering the extended Boussinesq equations as governing equations using MIKE21 software. The result of discontinuous breakwater was compared with a beach without breakwater. The results showed that the gap dramatically effects on surface elevation from shore line to offshore. It is also evident from results that with approaching the center of the gap, fluctuation of surface elevation is generated. It is because of passing longshore currents towards offshore through the gap which leads to an increase in sediment transportation rate. Nevertheless, transferring water mass from breakwater gap results in powerful rip currents leading to high changes on longshore wave profile.

• Journal of Ocean Engineering and Technology
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• v.28 no.4
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• pp.331-337
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• 2014

We analyzed the 3-D characteristics of the dynamic response of seabed around a submerged breakwater due to wave loading using a 3-D numerical scheme (LES-WASS-3D). Using our model, which considers the wave-structure-sandy seabed interactions in a 3-D wave field, we were able to investigate the 3-D characteristics of the pore-water pressure in the seabed around the submerged breakwater under various incident wave conditions. To verify the 3-D numerical analysis method suggested in this study, we compared the numerical results with the existing experimental results and found good agreement between them. The numerical analysis reveals that high pore-water pressure in the seabed is generated below a large wave height at the front slope of the submerged breakwater. It was also shown that the non-dimensional pore-water pressure in the seabed increases as the wave period increases because the wave energy dissipation decreases on the submerged breakwater and seabed as the wave period increases.

• Journal of Navigation and Port Research
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• v.37 no.3
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• pp.283-289
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• 2013

Wave profiles coming with oblique angle to trapezoidal submerged breakwater on the porous seabed are computed numerically by using a boundary element method. The analysis method is based on the wave pressure function with the continuity in the analytical region including fluid and structure. When compared with the existing results on the oblique incident wave, the results of this study show good agreement. The fluctuation of wave profiles is increased in the rear of the submerged breakwater due to the increase of the transmission coefficient, as the incident angle increases. In addition, in the case of the wave profiles passing over the submerged breakwater on porous seabed, it is able to verify that the attenuation of wave height occurs more significantly due to the wave energy dissipation than that of passing over the submerged breakwater on the impermeable seabed. The results indicate that wave profile own high dependability regarding the change of oblique incident waves and porous seabed. Therefore, the results of this study are estimated to be applied as an accurate numerical analysis referring to oblique incident waves and porous seabed in real sea environment.

• Journal of Ocean Engineering and Technology
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• v.16 no.6
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• pp.7-17
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• 2002

Recently, artificial rocks, instead of buoys, have been placed on the submerged breakwater to indicate its location. The accurate estimation of wave forces on these rocks is deemed necessary for their stability design. Characteristics of the wave force, however, are expected . to be very complicated because of the occurrence of breaking or post-breaking waves. In this regard, wave forces exerted on an artificial rock have been investigated in this paper. The maximum wave force has been found to strongly dependent on the location and shape of the artificial rock that is placed on the submerged breakwater. The plunging breaker occurs near the loading cram edge of a submerged breakwater, which cause impulsive breaking wave force on the rock. Using the Morison equation, with the velocity and acceleration at the front face of the artificial rock and varying water surface level, it is possible to estimate wave forces, even impulsive breaking wave forces, that are acting on the rock installed on a submerged breakwater. The vertical wave force is also found to depend, significantly, on the buoyant force.

• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.573-580
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• 2019

A submerged breakwater is a coastal structure built under water with excellent landscape. The depth of the crest of the breakwater should be maintained at more than a certain level in order for the submerged breakwater to control waves properly. This means that the effect of blocking waves deceases sharply at high tide in coastal areas with large tidal differences. In this study, we proposed a Tide-Adapting Submerged Breakwater (TA-SB) to overcome this problem, and then we conducted hydraulic model experiments to evaluate the performance of the TA-SB for controlling waves. The experimental results showed that the tapered wings attached to the crest of the TA-SB helped induce forced breaking waves. In particular, they were very effective in blocking waves and attenuating wave energy at high tide. In addition, the wave control performance of the proposed TA-SB was far superior to the Tide-Adapting Low-Crested Structure (TA-LCS) of the previous study.

• Journal of Coastal Disaster Prevention
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• v.5 no.4
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• pp.203-210
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• 2018

It is generally known that submerged breakwaters can reduce the incoming wave energy without disturbing the beach scenery. However, a submerged breakwater is also able to cause a setup of the sea level in the protected area which is also called as water piling-up. Since the piling-up can result in longshore currents, sediment transports, and unexpected beach erosion, understanding about the piling-up process is required prior to designing the nearshore structures. In this study, the water piling-up behind a submerged breakwater is assessed in the time of storm events. For the study area, Anmok beach in Gyeonso-dong, Gangwon-do is selected. 1-year, 5-year, 10-year, and 50-year return-values were derived from Peaks-Over-Threshold(POT) method and those are applied as offshore boundary conditions for the numerical simulation. The numerical results of the piling-up were assessed with regard to the wave steepness and the height of the submerged breakwater. With increase of both significant wave height and the height of the submerged breakwater, the piling-up parameter is also increased which can lead to erosion of dry beach behind the structure.