혼성방파제에 작용하는 3차원 파압구조에 미치는 위상차의 영향

허동수(Hur Dong-Soo),염경선(Yeom Gyeong-Seon),배기성(Bae Ki-Seong) 대한토목학회 2006 대한토목학회논문집 B Vol.26 No.5B

In designing the coastal structures, the accurate estimation of wave forces on them is very important. Recently, the empirical formulae such as Goda formula are widely used to estimate wave forces, as well as 2-D hydraulic and numerical model tests. But, sometimes, these estimation methods mentioned above seem to be unreasonable to predict 3-D structure of wave pressure on the coastal structures with 3-D plane arrangement in the real coastal area. Especially, in case of consideration of phase difference at harbor and seaward sides of the large-sized coastal structures like a composite breakwater, it is easily expected that the real wave pressures on each section of coastal structure have 3-D distribution. A new numerical model of 3-D Large Eddy Simulation, which is applicable to permeable structure, is developed to clarify the 3-D structure of wave pressures acting on coastal structure. The calculated wave forces on 3-D structure installed on the submerged breakwater show in good agreement with the measured values. In this study, the composite breakwater is adopted as a representative structure among the large-sized coastal structures and the 3-D structure of wave pressures on it is discussed in relation to the phase difference at harbor and seaward sides of it due to wave diffraction and transmitted wave through rubble mound. 현재 해안구조물의 설계시에는 현지관측을 토대로 한 Goda식(Goda, 1974)과 같은 경험식이나 2차원적인 수리수치모형실험을 통한 파력값을 많이 사용하고 있다. 하지만 이러한 2차원 해석결과들은 실해역에 설치된 구조물의 평면배치형상에 따라 변화하는 작용파력의 3차원 구조를 재현하기에는 무리가 있는 듯 하다. 특히, 혼성방파제와 같은 대형구조물의 항외측과 항내측에서 위상차가 발생하는 경우에는 구조물의 단면별로 파력이 각기 다르게 작용할 것으로 판단된다. 본 연구에서는, 해안구조물에 작용하는 파력의 3차원구조를 명확히 하기 위하여, 투과성구조물 및 쇄파현상도 적용이 가능한 기존의 수치해석기법(Hur and Mizutani, 2003)에 Large Eddy Simulation(LES)기법을 도입한 새로운 3차원 수치해석기법을 제안하였으며, 이 기법을 이용하여 얻어진 잠제상 구조물에서의 작용파력 계산치를 기존의 수리모형실험치와 비교한 결과, 좋은 일치성을 확인하였다. 또한, 대형해안구조물 중 혼성방파제를 본 연구의 대상구조물로하여, 사석마운드로의 투과 및 개구부로의 회절의 영향으로 인해 발생하는 위상차를 고려한 3차원 파력구조에 관해 논의하였으며, 2차원 해석으로는 규명할 수 없었던 3차원적인 동적 파력특성을 파악할 수 있었다.

경남연안의 지역특성에 따른 폭풍해일고의 변동

허동수(DONG-SOO HUR),염경선(GYEONG-SEON YEOM),김지민(JI-MIN KIM),김도삼(DO-SAM KIM),배기성(KI-SUNG BAE) 한국해양공학회 2006 韓國海洋工學會誌 Vol.20 No.3

Each year, the south coast of Korea is badly damaged from storm surge. The damages are greatly dependent upon the local peculiarities of the region where the storm surge occurs. So, in order to prevent/reduce recurrence of the disaster, it is very important to investigate the fluctuation characteristics of the storm surge height, related to the local peculiarities at each coastal area where occurrence of the disaster is expected. In this paper, using the numerical model, the storm surge was simulated to examine its fluctuation characteristics at the Gyeongnam coast (southeast coast of Korea). Typhoons of Sarah (5914), Thelma (8705) and Maemi (0314), which caused terrible damage to the coastal area in the southeast coast of Korea in the past, were used forstorm surge simulations. Moreover, the storm surge due to virtual typhoons, which were combined the characteristics of each proposed typhoons (Maemi, Sarah, Thelma)with the travel route of other typhoon, was predicted. As expected, the results revealed that the storm surge heights are enhanced at the coastal regions with the concavity like a long-shaped bay. Also, the storm surge heights, due to each typhoon, were compared and discussed at major points along the Gyeongnam coast, related to the local peculiarities,as well as the characteristics and the travel route of typhoon.

투과성잠제 주변의 파동장 해석을 위한 2-D 및 3-D 수치계산의 비교

허동수(Hur, Dong-Soo),최동석(Choi, Dong-Seok),이우동(Lee, Woo-Dong),염경선(Yeom, Gyeong-Seon) 한국해안해양공학회 2008 한국해안해양공학회 논문집 Vol.20 No.4

본 연구에서는 투과성잠제 주변의 파동장 해석을 위한 2-D 수치해석기법과 3-D 수치해석기법에 의한 결과를 비교하기 위하여 투과성구조물에 의한 유체저항(관성저항, 층류저항 및 난류저항)을 고려할 수 있는 수치해석기법을 이용하고, 난류모델로서 LES 모델을 도입하여 기존에 수행되었던 수리모형실험과의 비교를 통하여 검증하였다. 수치해석결과로부터 투과성잠제의 배후에서 2-D해석에 의한 결과가 3-D해석의 경우보다 높은 파고분포를 나타내었으며, 잠제 주변의 평균류에 대해서도 비교, 논의하였다. The aim of this study is to compare the numerical results obtained by 2-D and 3-D models which are used to examine the wave field around a permeable submerged breakwater. At first, the numerical model, which is able to consider the flow through a porous medium with inertial, laminar and turbulent resistance terms and determine the eddy viscosity with LES turbulent model, is used and validated by comparing with existing experimental data. And then, the numerical test on the wave field around a permeable submerged breakwater is performed. It is revealed from the numerical results that, at the onshore side of the submerged breakwater, the wave height by 2-D analysis is higher than that by 3-D analysis. Also, the time-averaged mean flow around a submerged breakwater is discussed in detail.

[기술노트] 무반사 조파시스템을 적용한 3차원 수치파동수조에서 다방향불규칙파의 조파방법

허동수(Hur Dong-Soo),이우동(Lee Woo-Dong),전호성(Jeon Ho-Sung),염경선(Yeom Gyeong-Seon) 대한토목학회 2011 대한토목학회논문집 B Vol.31 No.3B

본 연구에서는 무반사 조파시스템을 적용한 3차원 수치파동수조에서 다양한 다방향불규칙파의 조파 방법에 의한 다방향불규칙파의 방향분포함수에 대해서 검토하였다. 그 결과 무반사 조파가 가능한 3치원 수치파동수조(LES-WASS-3D)에서 다방 향불규칙파의 조파가 가능한 것을 확인하였다. In this study, generation methods of 3-D multi-directional random wave are examined using the fully non-linear numerical model with non-reflected wave generation system (LES-WASS-3D). Directional distribution functions obtained by EMLM method are compared for multidirectional random waves generated by various generation methods. As a results, it is revealed that multi-directional wave field can be simulated using LES-WASS-3D.

파ㆍ수중방파제ㆍ지반의 비선형 동적응답에 관한 연구

허동수(DONG-SOO HUR),김창훈(CHANG-HOON KIM),염경선(GYEONG-SEON YEOM),김도삼(DO-SAM KIM) 한국해양공학회 2005 韓國海洋工學會誌 Vol.19 No.6

Recently, various-shaped coastal structures have been studied and developed. Among them, the submerged breakwater became generally known as a more effective structure than other structures, because it not only serves its original function, but also has the ability to preserve the coastal environment. Most previous investigations have been focused on the wave deformation and energy dissipation due to submerged breakwater, but less interest was given to their internal properties and dynamic behavior of the seabed foundation under wave loadings. In this study, a direct numerical simulation (DNS) is newly proposed to study the dynamic interaction between a permeable submerged breakwater over a sand seabed and nonlinear waves, including wave breaking. The accuracy of the model is checked by comparing the numerical solution with the existing experimental data related to waveㆍpermeable submerged breakwaterㆍseabed interaction, and showed fairly nice agreement between them. From the numerical results, based on the newly proposed numerical model, the properties of the wave-induced pore water pressure and the flow in the seabed foundation are studied. In relation to their internal properties, the stability of the permeable submerged breakwater is discussed.

잠제 설치 연안역의 파동장에 미치는 해안곡률의 영향

허동수(Hur Dong-Soo),이우동(Lee Woo-Dong),염경선(Yeom Gyeong-Seon) 대한토목학회 2009 대한토목학회논문집 B Vol.29 No.5B

본 연구에서는 잠제가 설치된 연안역에서 해안의 곡률반경이 잠제 주변 파동장에 미치는 영향을 파악하기 위하여 파ㆍ구조물ㆍ해빈/해저지반의 상호작용을 해석할 수 있는 3차원 수치모델 LES-WASS-3D를 이용하여 시뮬레이션을 실시하였다. 먼저 기존의 수리모형실험결과와 비교ㆍ검토를 통하여 타당성과 유효성을 확인하였으며, 수치실험을 통해 얻어진 수치해석결과로부터 잠제 주변의 파고분포, 평균수위분포, 상층흐름분포, 평균류분포 그리고 연안에서의 처오름 높이분포를 비롯한 잠제주변의 3차원적 수리특성에 미치는 해안곡률의 영향에 관하여 고찰하였다. The aim of this study is to examine the effect of beach curvature on wave fields in coastal area with Submerged Breakwaters using the 3D numerical model that is able to simulate directly interaction of WAveㆍStructureㆍSandy beach (LES-WASS-3D). At first, the adopted model was validated through the comparison with an existing experimental data and showed fairly nice agreement. And then, the numerical simulations have been performed to investigate the effect of according to the variation of beach curvature. Based on the numerical results, the wave height, mean surface elevation, mean flow around submerged breakwaters and longshore distributions of run-up height have been discussed in relation to the variation of beach curvature.

해저지반 상부에 설치된 침매터널에 작용하는 동수압에 관한 수치실험

허동수(Hur, Dong Soo),김창훈(Kim, Chang Hoon),염경선(Yeom, Gyeong Seon),김도삼(Kim, Do Sam) 한국해안해양공학회 2005 한국해안해양공학회 논문집 Vol.17 No.4

지금까지 침매터널에 대한 대부분의 연구들은 건설기술자의 경험에 바탕을 둔 연구들이었다. 공학적인 관점에서 파랑하중에 의한 침매터널의 안정성은 지반기초의 거동에 큰 영향을 받으므로 파·지반·침매터널의 상호작용에 대한 이해는 매우 중요하다. 본 연구에서는 파·지반·침매터널의 상호작용의 메커니즘에 대한 이해를 위하여 부산-거제간 연결도로 민간투자사업 구간 중 침매터널 구간에 직접수치해석기법을 적용하여 침매터널 주변의 지반 및 피복층 내에서 파랑하중에 의한 간극수압, 와도 및 흐름의 특성을 종합적으로 살펴보았다. 또한 다양한 파랑조건 및 피복층의 평균입경변화에 따른 비선형성의 파랑과 침매터널 및 지반의 상호작용이 침매터널의 안정성과 관련하여 논의되었다. Most immersed tunnels investigated have been investigated based on the engineer's experience with design and construction. From engineering point of view, it is very important to understand the wave interaction with the seabed and immersed tunnel, since the stability of an immersed tunnel depends largely on the behavior of the seabed foundation. In this study, for the first stage research to find out the mechanism of the wave interaction with the seabed and immersed tunnel, the benchmarking method called as direct numerical simulation (DNS) was employed to analyze comprehensively the wave-induced pore water pressures, vorticity and flows in seabed or inside rubble stone around the immersed tunnel. The immersed tunnel is modeled based on Busan-Geoje fixed link project in Korea, which is now on the stage of planning. Moreover, the nonlinear water wave interaction with an immersed tunnel/its seabed foundation was thoroughly examined with regard to the stabilities of the immersed tunnel subjected to various water wave conditions, median grain size and so forth.

LES-WASS-3D를 이용한 연안에서의 침수시뮬레이션

허동수(DONG-SOO HUR),이우동(WOO-DONG LEE),염경선(GYEONG-SEON YEOM) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.4

The aim of this study is to investigate the inundation characteristics over coastal area due to the variation of sea level and plane arrangement of manholes using the 3D numerical model that is able to simulate directly interaction of WAveㆍStructureㆍSandy beach(LES-WASS-3D). At first, The adopted model was validated through the comparison with an existing experimental data and showed fairly nice agreement. And then, the inundation characteristics over coastal area are discussed in relation to the variation of sea level and plane arrangement of manholes.