• Title/Summary/Keyword: Movable breakwater

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Numerical Analysis of Hydrodynamic Performance of a Movable Submerged Breakwater (가동식 잠수 방파제의 유체동력학적 성능 수치해석)

  • Koo, Weon-Cheol;Kim, Do-Hyun
    • 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.

Numerical Analysis of Hydrodynamic Performance of a Movable Submerged Breakwater Using Energy Dissipation Model (에너지 소산 모델을 이용한 잠수된 가동식 방파제의 유체동역학적 성능 수치해석)

  • Kim, Do-Hyun;Koo, Weon-Cheol
    • Journal of the Society of Naval Architects of Korea
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    • v.49 no.4
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    • pp.287-295
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    • 2012
  • Hydrodynamic performance of a movable submerged breakwater was analyzed using energy dissipation model. Based on two-dimensional boundary element method the equation of motion including a viscous dissipation term proportional to velocity squared was solved by Newton-Raphson method. Energy dissipation coefficients as well as reflection and transmission coefficients of a submerged flat plate were calculated with various plate lengths and thickness. Both real and imaginary components of body displacement and forces were used to solve the motion of breakwater accurately. The effect of the magnitude of dissipation coefficient on the body displacement was evaluated. The results from the potential theory with no dissipation term were found to be an overestimate in resonance frequency.

A Study on the Deformation of the Topographic Feature due to the Construction of the datached Breakwater in the River-mouth Area (하구역에 설치된 이안제에 의한 하구지형변화에 관한 연구)

  • 양윤모;이문찬
    • Water for future
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    • v.18 no.4
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    • pp.327-333
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    • 1985
  • The flow pattern of the nearshore current generated around the breached breakwaters and river-mouth was simulated by numerical model in the case of the inclined incident wave without river discharge when the detached breakwaters were installed at the river-mouth area for the protection against the blockade of the river-mouth. The validity of the numerical model was testified y comparision with the results obtained through the hydraulic model test at the fixed bed. The deformation of the topographic features around the river-mouth and the detached breakwaters was examined through the three-dimensional hydraulic model test at the movable bed. The usefulness of the detached breakwater work for the protection against the blockade of the river-mouth was identified by the experimental results.

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The Prediction of Littoral Transport in the Vicinity of Coastal Structures (해안구조물 주위의 표사이동예측)

  • 김규한;이봉희
    • Water for future
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    • v.20 no.1
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    • pp.63-72
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    • 1987
  • This study describes a procedure of movable bed model tests and discusses the similitude with a view to state of the art. The prediction of littoral transport in the vicinity of coastal structure of nuclear power #9, 10 has been attempted. From the result of the present movable model study, it was found that the offshore breakwater is more excellent than the groyne and the rip-current barrier for the prevention against in take siltations and for the stability of investigated coastal structure of nuclear power plant.

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Performance Analysis of OWC-MB Hybrid Wave Energy Harvesting System Attached at Caisson Breakwater (케이슨방파제 부착 OWC-MB 복합형 파력발전시스템 성능해석)

  • Seo, Ji Hye;Park, Woo-Sun;Lee, Joong Woo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.35 no.3
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    • pp.589-597
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    • 2015
  • Wave energy harvesting system using OWC(Oscillating Water Column) and MB (Movable Body) attached at the caisson breakwater was studied. This system was suggested to maximize wave energy extraction using resonant phenomena of oscillating water column and buoy in wave channel (Park et al., 2014). Not only incident waves but also reflected waves from the breakwater can be used as sources of exciting force for harvesting wave energy efficiently. Using Galerkin finite model based on the linear wave theory (Park, 1991), the performance of the system was evaluated for various damping ratios of power take off system. Numerical results show that the proposed system is excellent in efficiency compared with that of conventional system and the performance of the system is governed by the resonance of oscillating water column in the wave channel. In addition, the additional efforts to minimize viscous damping was found to be necessary because viscous damping occurring in the channel and around the moving buoy is significant in generation efficiency.

Experimental Study on Effectiveness of Wave Reduction and Prevention Erosion of Nourishment Sand Using the Cell Group (Cell Group을 이용한 파랑저감 및 양빈사 유실방지에 관한 실험적 연구)

  • Park, Sang Kil;Park, Hong Bum;Kim, Young Hwan
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.29 no.5
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    • pp.269-277
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    • 2017
  • Recently, a submerged breakwater has been installing to prevent the erosion of shoreline everywhere. Artificially submerged breakwater is made to minimize the loss of nourishment sand beach erosion. For this reason, it has been indiscriminately constructed submerged breakwater that is planned in the country throughout. However, maintenance purposes to keep the shoreline of the beach is a method that is quite a few problems. There are also disadvantages such as expensive construction costs, ocean space utilization, water pollution and shoreline modification. In addition, person of utilizing the space of the ocean leisure does not like that because of the disconnection of ocean space. The beaches such as Gwanganri are artificially supplying nourishment sand to maintain the beach. The flexible construction method refers to a structure that is installed as a flexible material instead of submerged breakwater to prevent the loss of nourishment sand. In order to develop a new method to mitigate shoreline erosion, this study was carried out a hydraulic model experiment by installing a cell group as an example of the flexible method. Namely, in order to prevent the loss of nourishment sand, we decided to develop a new method that can mitigate the degree of beaches erosion by using cell group instead of submerged breakwater. In the two dimensional fixed hydraulic experiment, was carried out the effect reducing of wave height and the rate of low reflection due to the installation of the cell group. In movable bed experiment, the capture rate of the nourishment sand and the erosion prevention rate of the nourishment sand was performed for stability of shoreline. Therefore, according to the results of the hydraulic tests, it was possible to maintain the stable beaches due to installing the cell group on the erosion beaches, due to the effect of reducing wave height, the low reflection, the erosion prevention rate of nourishment sand, the high capture rate of nourishment sand.

A Practical Algorithm to Simulate Erosion of On-Shore Zone (실용적 해안선 후퇴 반영 알고리즘)

  • Kim, Hyoseob;Lee, Jungsu;Jin, Jae-Youll;Jang, Changhwan
    • Journal of Wetlands Research
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    • v.15 no.3
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    • pp.423-430
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    • 2013
  • An algorithm to allow shoreline movement during numerical experiment on sediment transport, deposition or resuspension for general coastal morphology is proposed here. The bed slope near shoreline, i.e. mean sea level, is influenced by bed material, tidal current, waves, and wave-induced current, but has been reported to remain within a stable range. Its annual variation is not large, either. The algorithm is adjusting the bathymetry, if the largest bed slope within shoreline band exceeds a given bed slope due to continuous erosion at zones below the shoreline. This algorithm automatically describes retreat of shoreline caused by erosion, when used within a numerical system. The algorithm was tested to a situation which includes a continuous dredging at a point, and showed satisfactory development of concentric circle contours. Next, the algorithm was tested to another situation which includes sinking of eroded part of bed plate, and produced satisfactory results, too. Finally, the algorithm was tested to a movable-bed laboratory experimental conditions. The shoreline movement behind detached breakwater was reasonably reproduced with this algorithm.