• 대한토목학회논문집
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• 제34권5호
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• pp.1463-1476
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• 2014

본 연구에서는 파랑과 흐름이 공존하는 하구 주변의 수리특성 및 지형변동특성을 이해하기 위하여 새롭게 3차원 지형변동 모델을 개발함과 더불어 3차원 파동장 모델과 양방향 연성 수치모델을 제안하였다. 그리고 파랑-흐름 공존장에서의 파고분포, 연직유속분포, 해저파이프라인 저면의 지형변동 및 고립파 내습 시에 해빈 저면 부유사 농도의 시간분포에 관한 수리모형실험결과들과 비교 분석하여 개발한 연성 수치모델을 검증하였다. 이로써 본 연구에서 개발한 연성 수치모델의 타당성 및 유효성을 확보할 수 있을 뿐만 아니라, 이 연성 수치모델이 파랑과 흐름이 공존하는 하구지역의 지형변동 예측에 적용이 가능한 것을 확인하였다.

• 한국해양공학회지
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• 제30권6호
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• pp.484-497
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• 2016

In order to understand the characteristics of the topography change in front of an impermeable breakwater, a coupled model for a two-way analysis of the existing LES-WASS-2D and newly developed morphodynamic model was suggested. A comparison to existing experimental results revealed that the results computed using the 2-D hydro-morphodynamic model were in good agreement with the experimental results for the wave form, pore water pressure in the seabed, and topographical change in front of a submerged breakwater. It was shown that the two-way model suggested in this study is applicable to a morphological change in the seabed around a submerged breakwater. Then, using the numerical results, the topographical changes in front of an impermeable submerged breakwater were examined in relation to partial standing waves. Moreover, the characteristics of the local scour depths in front of them are also discussed in relation to incident wave conditions, sediment qualities, and submerged breakwater shapes.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(1)
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• pp.760-762
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• 2005

• 한국해양공학회지
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• 제33권6호
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• pp.581-589
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• 2019

In order to understand the characteristics of beach deformation, in this study, numerical simulations were conducted using a 3-D hydro-morphodynamic model (HYMO-WASS-3D) to analyze the characteristics of beach deformation due to the coastal groundwater levels. HYMO-WASS-3D directly analyzed the nonlinear interaction between the hydrodynamic and morphodynamic processes in the coastal area. The simulation results of HYMO-WASS-3D showed good agreement with the experimental results on the changes in the profile of the beach in the surf and swash zones. Then, numerical simulations were conducted to examine the characteristics of beach deformation due to the variation of the level of the coastal groundwater. As a result, the beach profiles were examined in relation to the wave breaking in the surf zone and the wave uprush and backwash in the swash zone due to the differences in the water levels. This paper also discussed the temporal and spatial distributions of the velocities, vorticities, and suspended sediments in the surf and swash zones with various levels of the coastal groundwater.

• International Journal of Naval Architecture and Ocean Engineering
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• 제2권2호
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• pp.68-74
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• 2010

The development of a numerical model using the fractional area/volume obstacle representation (FAVOR) method for predicting a nearshore current field bounded by complicated geometric shapes, and a three-dimensional (3D) beach evolution was described in this article. The 3D model was first tested against three cases to simulate the nearshore current fields around coastal structures, a river mouth, and a large scale cusp bathymetry. Then, the morphodynamic model tests, which are adopting the nearshore current model, were applied for the computations of beach evolution around a detached breakwater and two groins. It was confirmed that the presented model associated with the FAVOR method was useful to predict the nearshore current field in the vicinity of the complicated geometric shapes. Finally, the model was applied to a tombolo formation in a field site of Kunnui fishery port, which is located in Hokkaido, Japan.

• 한국해양공학회지
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• 제36권4호
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• pp.251-269
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• 2022

The process-based XBeach model has numerous empirical parameters because of insufficient understanding of hydrodynamics and sediment transport on the nearshore; hence, it is necessary to calibrate parameters to apply to various study areas and wave conditions. Therefore, the calibration process of parameters is essential for the improvement of model performance. Generally, the trial-and-error method is widely used; however, this method is passive and limited to various and comprehensive parameter ranges. In this study, the Generalized Likelihood Uncertainty Estimation (GLUE) method was used to estimate the optimal range of three parameters (gamma, facua, and gamma2) using morphological field data collected in Maengbang beach during the four typhoons that struck from September to October 2019. The model performance and optimal range of empirical parameters were evaluated using Brier Skill Score (BSS) along with the baseline profiles, sensitivity, and likelihood density analysis of BSS in the GLUE tools. Accordingly, the optimal parameter combinations were derived when facua was less than 0.15 and simulated well the shifting shape, from crescentic sand bar to alongshore uniform sand bars in the surf zone of Maengbang beach after storm impact. However, the erosion and accretion patterns nearby in the surf zone and shoreline remain challenges in the XBeach model.

• Wind and Structures
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• 제36권2호
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• pp.75-90
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• 2023

Turbulent wind flow over hilly terrains has been extensively investigated in the scientific literature and main findings have been included in technical standards. In particular, turbulent wind flow over nominally two-dimensional hills is often adopted as a benchmark to investigate wind turbine siting, estimate wind loading, and dispersion of particles transported by the wind, such as atmospheric pollutants, wind-driven rain, windblown snow. Windblown sand transport affects human-built structures and natural ecosystems in sandy desert and coastal regions, such as transport infrastructures and coastal sand dunes. Windblown sand transport taking place around any kind of obstacle is rarely in equilibrium conditions. As a result, the modelling of windblown sand transport over complex orographies is fundamental, even if seldomly investigated. In this study, the authors present a wind-sand tunnel test campaign carried out on a nominally two-dimensional sinusoidal hill. A first test is carried out on a flat sand fetch without any obstacle to assess sand transport in open field conditions. Then, a second test is carried out on the hill model to assess the sand flux overcoming the hill and the morphodynamic evolution of the sand sedimenting over its upwind slope. Finally, obtained results are condensed into a dimensionless parameter describing its sedimentation capability and compared with values resulting from other nominally two-dimensional obstacles from the literature.

• 한국수자원학회논문집
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• 제47권10호
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• pp.907-919
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• 2014

본 연구는 LES와 유사이동 모형을 이용하여 군말뚝 주변 세굴과정 및 특성의 수치모의에 관한 내용이다. 군말뚝 주변에서 세굴 및 퇴적은 말뚝간격에 크게 영향을 받았다. 무차원 말뚝간격이 3.75보다 작은 경우에는 군말뚝 주변 국부세굴 뿐만 아니라 단면축소세굴이 발생하였다. 반면 무차원 말뚝간격이 3.75 이상이면 단면축소세굴은 사라지고 각각의 말뚝에서 국부세굴만발생하였다. 상류에 위치한 말뚝에서 세굴 심변화는 단일 말뚝의 경우와 유사한 경향을 보였지만 하류에 위치한 말뚝근처에서 세굴심은 상류말뚝 존재 때문에 세굴심이 낮게 나타났고 경향성도 상당히 다름을 보였다. 군말뚝 주변의 무차원 최대 세굴심은 말뚝간격이 증가할수록 감소하였다.

• 한국해안·해양공학회논문집
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• 제26권2호
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• pp.96-102
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• 2014

하구역의 지형변화를 예측하기 위해 3차원 해빈 변형 모델을 통한 계산이 수행되었다. 본 모델은 수심적분을 기초로 한 준 3차원 연안흐름 모듈로 구성되며, 해안선의 변화, 부유사의 이송-확산 효과를 고려할 수 있다. 우선 모델의 성능을 확인하기 위해 3차원 해빈 변화 모델이 하구역 사주 형성에 적용되었다. 다음으로 동해에 인접한 Ara 강 하구에 모델이 적용되었다. Ara 강의 사주의 동계 변화가 재현되었으며 계산결과는 현장 관측 결과와 좋은 일치를 나타냈다.

• 한국연안방재학회지
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• 제5권4호
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• pp.183-192
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• 2018

In recent years, coastal areas have been suffering from coastal erosion, such as destruction of coastal roads and military facilities. In this study, the Delft3D model was used to analyze the sediment transport pattern due to seasonal characteristics of summer and winter waves in Anmok beach of the East coast. Typhoon and high waves are mainly are coming from ENE direction in the summer season and the flows occur in the northward. In winter, high waves are incident from NE and the flows occur in the southward. These seasonal patterns were simulated by using Delft3D model. As for model input, reanalysis wave data of the past 38 years were used, and the seasonal patterns were analyzed by dividing the whole year into summer and winter season. The grid point of the 38 year reanalysis data is far from the Anmok beach, so the three model grid systems (wide grid -> intermediate grid -> detailed grid) are constructed. Most of the flows in the NW direction occurred in summer, but erosion and deposition was alternated along the coastline. In winter, sediment was deposited near Gangnung Port due to the southern flow and the southern port. Strong winter waves compared to summer tend to cause deposition around Gangnung Port throughout the year.