• 해양환경안전학회지
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• 제20권3호
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• pp.312-317
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• 2014

In this paper, the wave run-up height and depression depth around air-water interface-piercing circular cylinder have been numerically studied. The Reynolds Averaged Navier-Stokes equations (RANS) and continuity equations are solved with Reynolds Stress model (RSM) and volume of fluid (VOF) method as turbulence model and free surface modeling, respectively. A commercial Computational Fluid Dynamics (CFD) software "Star-CCM+" has been used for the current simulations. Various Froude numbers ranged from 0.2 to 1.6 are used to investigate the change of air-water interface structures around the cylinder and experimental data and theoretical values by Bernoulli are compared. The present results showed a good agreement with other studies. Kelvin waves behind the cylinder were generated and its wave lengths are longer as Froude numbers increase and they have good agreement with theoretical values. And its angles are smaller with the increase of Froude numbers.

• 해양환경안전학회지
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• 제23권5호
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• pp.558-565
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• 2017

해양환경의 극한 환경조건에 노출 된 고정식 및 부유식 해양구조물의 안전성과 설계비용 효율성에 있어서 파랑-구조물 상호작용의 정확한 예측은 중요하다. 본 연구에서는 규칙파 중 원형 기둥에 대한 파랑-구조물 상호작용을 해석하였다. 3차원 이상유동(two-phase flow)을 해석하기 위해 오픈소스 전산유체역학 라이브러리인 오픈폼을 사용하였다. 4개의 원형기둥이 정사각형 배열을 이루고 있을 때 규칙파의 입사각도에 따른 상호작용을 해석하였다. 원형 기둥 구조물에서의 wave run-up을 입사파의 기울기에 따라 비교하였다. 원형 기둥과 입사파의 상호작용으로 인해 원형 기둥 사이에 높은 파가 생성되는 것을 확인하였다. 본 해석 결과는 구조물과 입사파의 상호작용에 의한 air gap에 대한 연구의 기초자료로 활용될 것으로 기대된다.

• 한국해양공학회지
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• 제24권1호
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• pp.53-59
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• 2010

In this study, an investigation of the shoreline changes at Song-do beach in Busan was carried out for a coastal improvement project to prevent damage from coastal disasters. From the results of the observed data, it is seen that the shoreline moves seaward under extreme wave conditions and moves leeward under normal wave conditions. The reason for this is wave run-up when wave conditions are extreme in summer. In addition, nourishment sand is moved seaward by wave run-up. Thus, the shoreline's slope is gently decreased. Therefore, the shoreline is moved seaward.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 춘계학술대회 논문집
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• pp.172-179
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• 2001

A numelical model has been developed for the permeable coastal structures to simulate hydraulic characteristics on the permeable slopes, which interact with internal flow field of the structures. The model includes hydraulics in the porous medium. Numerical model was calibrated using hydraulic model experiments performed in 2-D wave flume in the Institute of Orean Hydraulics in PKNU. Good agreement were obtained with the model which employed inertia resistance term than with the conventional model, PBREAK.

• 한국해안·해양공학회논문집
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• 제32권6호
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• pp.420-433
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• 2020

기존 케이슨방파제의 안정성을 높이기 위해 케이슨 전면 또는 후면에 추가로 신규 케이슨을 설치하여 보강하는 경우 박리에 의한 에너지 손실효과와 케이슨과 케이슨 사이의 공극률 변화에 따른 개별 원형케이슨에 작용하는 파력 및 파처오름 특성 평가는 중요하다. 본 연구에서는 고유함수전개법에 투과성판에서의 속도는 판 전후의 압력차에 선형적으로 비례한다는 Darcy의 법칙을 이용하여 원형케이슨들간의 공극률 계수 변화에 따른 2열 배치된 원형방파제에 작용하는 파랑 특성을 분석하였다. 수치해석의 신뢰성을 확보하기 위해 Sankarbabu et al.(2008)의 수치 해석결과와 비교를 수행하였으며, 다양한 변수에 따른 개별 이중 원형케이슨에 작용하는 파력 및 파처오름 특성을 나타내었다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.457-460
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• 2006

This study is to investigate the variation characteristics of run-up height over sandy beach due to the plane distribution of submerged breakwaters. In this study, Three-Dimensional numerical model with Large Eddy Simulation, which is able to simulate directly WAve Structure Seabed interaction (hereafter, LES-WASS-3D) has been newly developed. A comparison between the numerical model and existing experimental results was made to verify accuracy of newly proposed LES-WASS-3D model, and showed fairly nice agreement. In addition, based on the LES-WASS-3D model, the variation characteristics of run-up height over sandy beach are discussed with relation to the offshore distance and opening width of submerged breakwaters.

• 한국해양공학회지
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• 제27권3호
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• pp.43-52
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• 2013

In the present study, a flow analysis for estimating the wave loads acting on a stationary floating body inside a viscous numerical wave tank was performed using the commercial software FLUENT. The governing equations for the viscous and incompressible fluid motion were the continuity and Navier-Stokes equations, and a piston-type wavemaker was employed to reproduce wave environments. First, the optimal simulation conditions were derived through numerical tests for the wavemaker and wave absorber, and then the wave loads and wave run-up on a vertical truncated cylinder were estimated and compared with the experimental and other numerical results.

• Ocean Systems Engineering
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• 제4권3호
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• pp.169-183
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• 2014

For the reliable design of substructure supporting offshore wind turbines it is very important to reduce the effects of wave forces. Since the substructure is strongly influenced by the effects of wave forces as the size of substructure increases. In the present study, the hybrid substructure with multi-cylinder is newly suggested to reduce the effects of wave forces. Using diffraction theory the scattering waves in a fluid region are expressed by an Eigenfunction expansion method with three dimensional potential theory to calculate the wave force acting on the hybrid substructure. The wave force and wave run-up acting on the hybrid substructure is presented to examine the water wave interaction according to the variation of cylindrical size and the distance among cylinders. It is found that the suggested hybrid substructure with multi-cylinder is very useful to reduce the effects of wave forces acting on the substructure for offshore wind turbines.

• Ocean and Polar Research
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• 제40권2호
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• pp.87-98
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• 2018

It is widely known that infragravity waves can exert significant influence on wave run-up over beaches. Large run-ups can lead to overwash, flooding and severe coastal erosion. In spite of the importance of infragravity waves in relation to wave run-up and coastal erosion, few studies have been carried out with regard to the impact of infragravity waves on nearshore morphodynamics with respect to eastern beaches in Korea. The purpose of this study is to investigate the importance of infragravity waves in nearshore numerical modelling. For the study, XBeach model was set up to analyze morphodynamics in December 2016, in Ilsan beach which is located in Ilsan-dong, Ulsan Metropolitan City. After validation of the XBeach model, numerical experiments were conducted by using various directional spreading coefficients. As the directional spreading coefficients are increased, the effect of infragravity waves is also enhanced by narrowband frequency. With the increasing effect of infragravity waves, the amount of sediment transport is also increased and an erosion dominant pattern is found in the south part of Ilsan beach and a deposition pattern in the north part of the beach mainly due to the wave incident direction of NNE.

• 한국해양공학회지
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• 제19권3호
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• pp.18-24
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• 2005

Wave overtopping is one of the most important processes for the design of seawalls. The term "wave overtopping" is used here to refer to the processes where waves hit a sloping structure run up the slope and, if the crest level of the slope is lower than the highest run up level, overtop the structure. Wave overtopping is dependent on the processes associated with breaking wave. A numerical model based on Navier-Stokes equation and the Marker-density function for predicting wave overtopping of coastal structures is developed in this paper. In order to evaluate the present model, two simulations are tested. One is overflow without waves at vertical seawall, and the other is wave overtopping at sloping seawalls.