• 한국해양공학회지
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• 제19권2호
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• pp.1-11
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• 2005

In the present paper, the hydrodynamic properties of a Rahmen type flexible porous breakwater with dual fixed pontoon system interacting with obliquely or normally incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes hinged at the side edges of dual fixed pontoons, and a submerged horizontal membrane that both ends are hinged at the steel frames mounted pontoons. The dual vertical membranes are extended downward and hinged at bottom steal frame fixed into seabed. The wave blocking and dissipation mechanism and its effects of permeability, Rahmen type membrane and pontoon geometry, pretensions on membranes, relative dimensionless wave number, and incident wave headings are thoroughly examined.

• 한국해양공학회지
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• 제19권2호
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• pp.19-28
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• 2005

The present paper outlines the numerical investigation of the incident wave interactions with fully submerged and floating dual double hull pontoon/vertical porous membrane breakwaters. Two dimensional five fluid-domains hydro-elastic formulation was carried out in the context of linear wave body interaction theory to study the wave interaction with the double hull of pontoon-membranes. The submerged circular pontoon is consisted of double hulls, which is filled with water in the void space between the outer structure and inner solid buoyant structure. Hydrodynamic characteristics of the proposed system with dual floating double-hull-pontoons filled with water have been studied numerically for the various incident waves. This study is a beginning stage research for the dual double hull porous pontoons/vertical porous membranes breakwaters which is ideally designed in order to suppress significantly the transmitted and reflected waves simultaneously.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제5권1호
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• pp.14-21
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• 2002

In the present paper, the hydrodynamic properties of a Rahmen-type, flexible, porous breakwater interacting with obliquely or normal- incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes, hinged at the side edges of a submerged horizontal membrane. The dual vertical membranes are extended downward and hinged at seabed. The effects of permeability, Rahmen-type membrane breakwater geometry, pre-tensions on membranes, relative dimensionless wave number, and incident wave headings are thoroughly examined.

• 한국해양공학회지
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• 제15권2호
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• pp.22-32
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• 2001

The numerical investigation of obliquely incident wave interactions with fully submerged dual buoy/porous-membrane floating breakwaters placed in parallel with spacing is studied based on linear potential theory and Darcy's law. The numerical solutions are obtained by using a discrete-membrane dynamic model and second-kind modified Bessel function distribution over the entire boundaries of fluid regions. First, numerical solutions for an idealized dual submerged system without buoys are obtained. Second, a more practical dual submerged system with membrane tension provided by buoys at its tops is investigated by the multi-domain boundary element method particularly devised for dual buoy/porous-membrane problems with gaps. The velocity potentials of wave motion are coupled with porous-membrane deformation, and solved simultaneously since the boundary condition on porous-membrane is not known in advance. The effects of varying permeability on membranes and wave characteristics are discussed for the optimum design parameters of systems previously studied. The inclusion of permeability on membrane eliminates the resonances that aggravate the breakwater performance. The system is highly efficient when waves generated by the buoys and membranes were mutually canceled and its energy at resonance frequency dissipates through fine pores on membranes.

• 한국해양공학회지
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• 제16권5호
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• pp.7-14
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• 2002

in the present paper, the hydrodynamics properties of a Rahmen type flexible porous breakwater interacting with obliquely or normally incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes hinged at th side edges of a submerged horizontal membrane. The dual vertical membranes are extended downward and hinged at seabed. The effects of permeability, Rahmen type membrane breakwater geometry pre-tensions on membranes, relative dimensionless wave number, and incident Wave headings are thoroughly examined.

• 한국해양공학회지
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• 제15권2호
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• pp.11-21
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• 2001

The focus of this paper is on the numerical investigation of obliquely incident wav interactions with a system composed of fully submerged and floating dual buoy/vertical-flexible-membrane breakwaters placed in parallel with spacing between two systems. The fully submerged two systems allow surface and bottom gaps to enable wave transmission over and under the system. The problem is formulated based on the two-dimensional multi-domain hydro-elastic linear wave-body interaction theory. The hydrodynamic interaction of oblique incident waves with the combination of the rigid and flexible bodies was solved by the distribution of the simple sources (modified Bessel function of the second kind) that satisfy the Helmholz governing equation in fluid domains. A boundary element program for three fluid domains based on a discrete membrane dynamic model and simple source distribution method is developed. Using this developed computer program, the performance of various dual systems varying buoy radiuses and drafts, membrane lengths, gaps, spacing, mooring-lines stiffness, mooring types, water depth, and wave characteristics is thoroughly examined. It is found that the fully submerged and floating dual buoy/membrane breakwaters can, if it is properly tuned to the coming waves, have good performances in reflecting the obliquely incident waves over a wide range of wave frequency and headings.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2004년도 학술발표논문집 Proceedings of Coastal and Ocean Engineering in Korea
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• pp.150-159
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• 2004

In the present paper, the hydrodynamics properties of a Rahmen type flexible porous breakwater with dual fixed-pontoon system interacting with obliquely or normally incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes hinged a the side edges of dual fixed pontoons, and a submerged horizontal membrane that both ends are hinged at the steel frames mounted pontoons. The dual vertical membranes are extended downward and hinged at bottom steal frame fixed into seabed. The wave blocking and dissipation mechanism and its effects of permeability, Rahmen type membrane and pontoon geometry, pre-tensions on membranes, relative dimensionless wave number, and incident wave headings are thoroughly examined.

• 한국해양환경ㆍ에너지학회지
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• 제1권2호
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• pp.27-39
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• 1998

본 연구에서는 수면 밑 일정한 깊이에 잠긴 유연한 천이 파도중 수평으로 놓여 있을 때 유연막과 파도의 상호작용 문제를 살펴보았다. 파도와 유연막의 상호작용을 고려하기 위하여 선형 유탄성 이론을 사용하였다. 계산 예로 유연막의 형태, 잠긴 깊이 그리고 유연막에 걸리는 초기 장력을 변화시키면서 반사율과 투과율 그리고 유연막의 변형을 살펴보았다. 또한 Texas A&M 대학의 2차원 수조에서 모형실험을 수행하여 실험결과와 해석해를 비교하였다. 실험결과와 해석결과는 정성적으로 잘 일치하고 있음을 확인하였다. 개발된 설계 프로그램을 이용하여 설치 해역의 파랑 특성에 적합한 최적의 유연막 방파제를 설계, 제작할 수 있으리라 사료된다.

• 한국해안해양공학회지
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• 제9권4호
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• pp.182-193
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• 1997

본 연구에서는 유연성이 있는 막구조 방파제가 파도중 수평으로 놓여 있을 때 유연막에 의한 파랑제어 효과를 살펴보았다. 파도와 유연막의 상호작용을 고려하기 위하여 선형 유탄성 이론을 사용하였다. 계산예로 유연막의 형태, 잠긴깊이 그리고 유연막에 걸리는 초기 장력을 변화시키면서 반사율과 투과율 그리고 유연막의 변형을 살펴보았다. 또한 Texas A&M 대학의 2차원 수조에서 모형실험을 수행하여 해석해와 수치해를 비교하였다. 실험결과는 계산결과를 정성적으로 잘 따라가고 있음을 확인하였다. 개발된 설계 프로그램을 이용하여 설치 해역의 파랑 특성에 적합한 최적의 유연막 방파제를 설계. 제작할 수 있으리라 사료된다