• Title/Summary/Keyword: Wave Induced current

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Analysis of Wave and Current in Anmok Coastal Waters (안목해안의 파랑과 흐름 분석)

  • Lim, Hak-Soo;Kim, Mujong
    • Journal of Coastal Disaster Prevention
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    • v.4 no.1
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    • pp.7-19
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    • 2017
  • In this study, waves and currents observed by acoustic AWAC, VECTOR and Aquadopp Profiler in Anmok coastal waters were analysed to account for the variability of wave and current and to understand the mechanism of sediment transport generated by wave-induced current in the surf-zone. The monthly variation of wave and residual currents were analysed and processed with long-term observed AWAC data at station W1, located at the water depth of about 18m measured during from February 2015 to September 2016. Wave-induced currents were also analysed with intensive field measurements such as wave, current, suspended sediment, and bathymetry data observed at the surf-zone during in winter and summer. The statistical result of wave data shows that high waves coming from NNE and NE in winter (DEC-FEB) are dominant due to strong winds from NE. But in the other season waves coming from NE and ENE are prevalent due to the seasonal winds from E and SE. The residual currents with southeastern direction parallel to the shoreline are dominant throughout a year except in winter showing in opposite direction. The speed of ebb-dominant southeastern residual currents decreasing from surface to the bottom is strong in summer and fall but weak in winter and spring. By analysing wave-induced current, we found that cross-shore current were generated by swell waves mainly in winter with incoming wave direction about $45^{\circ}$ normal to the shoreline. Depending on the direction of incoming waves, longshore currents in the surf-zone were separated to southeastern and northwestern flows in winter and summer respectively. The variation of observed currents near crescentic bars in the surf-zone shows different direction of longshore and cross-shore currents depending on incoming waves implying to the reason of beach erosion generating the beach cusp and sandbar migration during high waves at Anmok.

A Study on the Numerical Model of Wave Induced Current around Nearshore Structure (연안역 구조물 주위에서의 해빈류의 수치해석에 관한 연구)

  • 민병형;이상화;김인철
    • Journal of Ocean Engineering and Technology
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    • v.5 no.1
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    • pp.55-63
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    • 1991
  • This study is to predict accurately the wave induced current accuring by the radiation stress which acts as the driving force around Nearshore structure. For the wave induced current, the depth integrated and time averaged governing equation of an unsteady nonlinear form is derived from the continuity and momentum equation of an incompressible fluid. Numerical solutions are obtained by a finite difference method for the governing equation. In the vicinity of a structure, computed flow patterns show good agreement with the hydraulic experimental data. The numerical results obtained by neglecting the convective term show a large change of alongshore and offshore current.

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Field Observation and Quasi-3D Numerical Modeling of Coastal Hydrodynamic Response to Submerged Structures

  • Yejin Hwang;Kideok Do;Inho Kim;Sungyeol Chang
    • Journal of Ocean Engineering and Technology
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    • v.37 no.2
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    • pp.68-79
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    • 2023
  • Even though submerged breakwater reduces incident wave energy, it redistributes the coastal area's wave-induced current, sediment transport, and morphological change. This study examines the coastal hydrodynamics and the morphological response of a wave-dominated beach with submerged breakwaters installed through field observation and quasi-3D numerical modeling. The pre-and post-storm bathymetry, water level, and offshore wave under storm forcing were collected in Bongpo Beach on the East coast of Korea and used to analyze the coastal hydrodynamic response. Four vertically equidistant layers were used in the numerical simulation, and the wave-induced current was examined using quasi-3D numerical modeling. The shore normal incident wave (east-northeast) generated strong cross-shore and longshore currents toward the hinterland of the submerged breakwater. However, the oblique incident wave (east-southeast) induced the southeastward longshore current and the sedimentation in the northeast area of the beach. The results suggested that the incident wave direction is a significant factor in determining the current and sediment transport patterns in the presence of the submerged breakwaters. Moreover, the quasi-3D numerical modeling is more appropriate for estimating the wave transformation, current, and sediment transport pattern in the coastal area with the submerged breakwater.

Simulation of the Temperature and Salinity Along $36^{\circ}N$ in the Yellow Sea with a Wave-Current Coupled Model

  • Qiao, Fangli;Ma, Ji-An;Yang, Yong-Zeng;Yuan, Yeli
    • Journal of the korean society of oceanography
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    • v.39 no.1
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    • pp.35-45
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    • 2004
  • Based on the MASNUM wave-current coupled model, the temperature and salinity structures along $36^{\circ}N$ in the Yellow Sea are simulated and compared with observations. Both the position and strength of the simulated thermocline are similar to data analysis. The wave-induced mixing is strongest in winter and plays a key role in the formation of the upper mixed layer in spring and summer. Numerical experiments suggest that in the coastal area, wave-induced mixing and tidal mixing control the vertical structure of temperature and salinity.

The Construction Plan of Breakwater by the Numerical Simulation (수치시뮬레이션에 의한 방파제의 시공계획)

  • Kim, Kyu-Han;Yoon, Seong-Jin;Kim, Young-Bok
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2006.11a
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    • pp.449-452
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    • 2006
  • The main external force of the harbor in east coast is wave. So, wave is the important cause of wave induced current and sediment transport due to wave in planning harbor structures. Therefore, it must be considered not only to secure the harbor tranquility but also the sediment transport due to wave induced current in planning the harbor. In this study, we studied on the influences of construction procedure on harbor tranquility and siltation using annual coastal line data and bathymetry data near breakwater. And it suggests that the construction procedure for the harbor tranquility and the best way for the decrease of harbor siltation.

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Surface current measurements using lagrangian Drifters in Anmok (소형 표류부이를 이용한 안목해안 표층 연안류 관측)

  • Lim, Hak Soo;Kim, Mujong;Shim, Jae-Seol
    • Journal of Coastal Disaster Prevention
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    • v.4 no.spc
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    • pp.245-253
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    • 2017
  • In this study, surface currents measured by small lagrangian GPS drifters (Aquadrifter) in Anmok coastal waters were analysed to account for the variability of nearshore surface current and wave-induced current to understand sediment transport mechanism near the crescentic bars in the surf-zone and near Kangneung breakwater and submerged breakwater in Anmok. The 8 times lagrangian drifter experiments were conducted mostly during in 2nd, 3rd, 4th intensive measurements in winter, summer, and spring seasons with long-term wave observation at the station W1. The analysed surface currents near the breakwaters in Anmok show that wave-induced currents at the middle of the submerged breakwater were separated and flowed toward the shoreline but offshore currents were dominant through the channels between the breakwaters. The longshore currents near the shoreline were flowed to the northwest (southeast) depending on the incoming waves from ENE (NNE). The surface nearshore offshore currents were generated mostly by waves and winds in case of high and low wave energy environments. Using the small-size lagrangian surface drifter experiments, we successfully measured longshore and offshore wave-induced currents in the surf-zone and near submerged breakwater close to Kangneung breakwater. The drifter experiment results show the availability of direct observation of nearshore surface currents to understand the mechanism of sediment transport analysing observed wave-induced current and ebb-current in the surf-zone generated by incoming waves and local winds.

2-DH Quadtree based Modelling of Longshore Current (연안류에 대한 2D-H 사면구조에 기초한 수치모델링)

  • 박구용
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.13 no.1
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    • pp.1-8
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    • 2001
  • Wave-induced currents drive nearshore transport processes, and hence an accurate understanding of wave-current interaction is required for proper management of coastal zone. This paper presents details of an adaptive quadtree grid based numerical model of the coupled wave climate and depth-averaged current field. The model accounts for wave breaking, shoaling, refraction, diffraction, wave-current interaction, set-up and set-down, mixing processes, bottom friction effects, and movement of land-water interface at the shoreline. The wave period- and depth-averaged governing equations arc discrctized explicitly by means of an Adarns¬Bashforth second-order finite difference technique on adaptive hierarchical staggered quadtree grids. Results from the numerical model are in reasonable agreement with the laboratory data of longshore current generated by oblique waves on a plane beach (Visser 1980, 1991).

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A Study on the Topography Change of Hyeya River and Jinha Beach (회야강 하구 및 진하해수욕장의 지형변화에 관한 연구)

  • 민병형;민일규;이동수
    • Journal of Ocean Engineering and Technology
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    • v.8 no.1
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    • pp.84-95
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    • 1994
  • In recent years Jin-Beach and Hyeya River mouth have experienced severe erosion phenomena. The cause of erosion is examined using a 3-dimensional nunumerical sediment transport model. The model is composed of three components : wave model, wave-induced current model and 3-dimensional sediment transport model. In the wave analysis component we consider refraction, diffraction and reflection based on Maruyama and Kajima method. For the wave-induced current model we use depth-integrated continuty equation and momentum equations. For the 3-dimensional sediment transport model we consider bed load and suspended load simutaneously. Model results obtained for Jin-ha Beach and Hyeya River mouth agreed well with experimental results.

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Numerical Simulation of Regular Wave Transformation due to Wave-induced Current over a Submerged Elliptic Shoal (수중타원형 천퇴를 통과하는 규칙파의 파랑쇄파류에 의한 변형)

  • Choi, Jun-Woo;Baek, Un-Il;Yoon, Sung-Bum
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.19 no.6
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    • pp.557-564
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    • 2007
  • The effect of wave and current interactions on regular wave transformation over a submerged elliptic shoal is investigated based on numerical simulations of the Vincent and Briggs experiment [Vincent, C.L., Briggs, M.J., 1989. Refraction-diffraction of irregular waves over a mound. Journal of Waterway, Port, Coastal and Ocean Engineering, 115(2), pp. 269-284]. The numerical simulations are conducted by constituting two numerical model systems: a combination of SWAN(a wave model) plus SHORECIRC(a current model) and a combination of REF/DIF 1(a wave model) plus SHORECIRC. A time dependent phase-resolving wave-current model, FUNWAVE, is also utilized to simulate the experiment. In the simulations, the breaking-induced currents defocus waves behind the shoal and bring on a wave shadow zone that shows relatively low wave height distributions. The computed results of the two model systems agree better with the measurements than the computed results obtained by neglecting wave-current interaction do. However, it is found that the radiation stresses for standing waves are misevaluated in the wave models. In addition, the results of FUNWAVE show very good agreement with the measurements. The agreement indicates that it is necessary to take into account the effect of breaking-induced current on wave refraction when wave-breaking occurs over a submerged shoal.

Characteristics of Wave-induced Currents using the SWASH Model in Haeundae Beach (SWASH 모형을 이용한 해운대 해수욕장의 해빈류 특성)

  • Kang, Min Ho;Kim, Jin Seok;Park, Jung Kyu;Lee, Jong Sup
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.27 no.6
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    • pp.382-390
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    • 2015
  • To simulate a complicated hydrodynamic phenomena in the surf zone, the SWASH model is used in Haeundae Beach. The SWASH model is well known as a model competing with the Boussinesq-type model in terms of near shore waves and wave-induced currents modelling. This study is aimed to the detailed analysis of seasonal waves and wave-induced current simulation in Haeundae Beach, where the representative seasonal wave conditions was obtained from hourly measured wave data in 2014 by Korea Hydrographic and Oceanographic Administration( KHOA). Incident wave conditions were given as irregular waves by JONSWAP spectrum. The calculated seasonal wave-induced current patterns were compared with the field observation data. In summer season, a dominant longshore current toward the east of the beach appears due to the effect of incident waves from the South and the bottom bathymetry, then some rip currents occurs at the central part of the beach. In the winter season, ESE incident waves generates a strong westward longshore currents. However, a weak eastward longshore currents appears at the restricted east side areas of the beach.