• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 한국해안해양공학회 2000년도 한국해안해양공학발표논문집 Proceedings of Coastal and Ocean Engineering in Korea
• /
• pp.103-112
• /
• 2000

Early efforts to model wave transformation from offshore to inshore were based on the ray theory which accounts for wave refraction due to changes in bathymetry and the diffraction effects were ignored. Prediction of nearshore waves with the combined effects of refraction and diffraction as well as reflection has taken a new dimension with the use of the mild-slope equation and the Boussinesq equation. (omitted)

• Proceedings of the Korea Water Resources Association Conference
• /
• 한국수자원학회 2011년도 학술발표회
• /
• pp.45-49
• /
• 2011

본 연구에서는 일본 전력중앙연구소에서 수행된 wave fission 수리모형실험 자료를 토대로 일차원 FUNWAVE 수치모형을 이용하여 wave fission 현상을 재현하는 수치모의를 수행하였다. FUNWAVE 수치모형은 Boussinesq 방정식을 지배방정식으로 사용하고 있으며 파의 분산효과와 비선형 효과를 고려할 수 있는 수치모형이다. 따라서 wave fission의 주된 발생원인인 분산효과와 비선형효과에 대한 고려를 통해 수치모의 결과는 수리모형실험의 관측치와 상당히 잘 일치함을 확인할 수 있었다. 또한, 본 연구에서는 추가적으로 해수의 흐름이 존재하는 경우를 가정하고 수로 내 일정한 유량의 흐름을 추가하여 wave fission 일차원 수치모의를 수행하였다. 수치모의 결과 파의 진행방향과 반대방향으로 흐름이 존재하는 경우 wave fission으로 인한 수면변위의 크기가 상대적으로 증가함을 확인할 수 있었으며 반대로 파의 진행방향과 동일한 방향으로 흐름이 존재하는 경우 wave fission으로 인한 수면변위의 크기가 상대적으로 감소함을 확인할 수 있었다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 한국수자원학회 2010년도 학술발표회
• /
• pp.546-550
• /
• 2010

흐름과 장파에 의하여 발생되는 난류의 subgrid scale mixing effects를 고려할 수 있는 수심적분형 모형(depth-integrated model)을 제시하였다. 완전비선형의 수심적분형 모형은 약분산(weakly dispersive) 환경에서 흐름의 회전성(rotational)을 고려하도록 perturbation approach를 이용하여 유도되었다. 동일한 방법을 이용하여 수심적분형 이송확산방정식(depth-integrated scalar transport equation)을 유도하였다. 방정식은 4차정확도의 유한체적기법을 이용하여 해석하였으며, 다양한 혼합양상을 보이는 흐름에 대한 수치모의를 수행하였다.

• Journal of the Korean Geotechnical Society
• /
• 제15권1호
• /
• pp.15-29
• /
• 1999

This study presents an analytical method of estimating the developed horizontal active thrusts against GRS-RW( Geosynthetic Reinforced Soil Retaining Wall) system adapted to the case of distanced surcharge. In addition, the design charts that could be used for preliminary design of GRS-RW system are presented. The proposed method of analysis uses two body translation mechanism as well as force polygon concept. taking into account the effect of facing's rigidity. Besides. the effect of tension cracks in c-\Phi$ soils, seismic effects and horizontal distance from the back face of wall to uniformly distributed surcharge loadings are also included. The results of horizontal active thrusts obtained from the developed method of analysis are compared with those from Jarquio's modified Boussinesq equation.

• Journal of the Korean Society of Marine Environment & Safety
• /
• 제28권1호
• /
• pp.161-167
• /
• 2022

Ocean waves passing through the underwater bar at a shallow depth experience a shoaling effect caused by decreasing water depth, a nonlinear interaction therein owing to steepening wave slope, and a wave dispersion effect as the water depth increases again. Because this problem includes many complicated phenomena, it is used as a good example of validating a theoretical development or a CFD method for ocean wave applications. Validation is performed mainly for regular waves by comparing the wave elevation patterns in the time domain with the experimental results. In this study, the spectral evolution of wave spectrum is investigated in the frequency domain when a CFD method such as OpenFOAM is applied for this problem. In particular, the effects of initial phase conditions as well as the nonlinear interaction among harmonic waves are studied.

• Journal of the Society of Naval Architects of Korea
• /
• 제39권1호
• /
• pp.38-48
• /
• 2002

Theoretical development to generate the directional extreme waves in model basin is established based on wave focusing method. The effects of associated parameters, such as the directional range, frequency width, and center frequency, are investigated in terms of wave focusing efficiency. The two different spectral models of constant wave amplitude and constant wave slope are applied to control the wave characteristics. The wave packets simulated by theory are compared with numerical results based on Boussinesq equation and FEM. Both controls of direction and frequency spectrum are essential to focus directional waves effectively. It is noticed that wave focusing ability depends on the frequency bandwidth of spectrum rather than center frequency, and both spectral models with same parameters result in the equivalent efficiency of wave focusing.

• Water for future
• /
• 제18권1호
• /
• pp.85-94
• /
• 1985

A method is developed for the separation of the major base flow in a river hydrograph combining the numerical techniques and the empirical methods. The linearized Boussinesq equation and the storage function are used to obtain the base flow recession. The shape of base flow curve made by the recharge of the groundwater table aquifer resulting from rainfall in determined by the Singh and Stall's graphical method, and the continuous from for the curve is approximated by the multiple and polynomial regression. this procedure was successfully tested for the separation of base flow and the establishment of hydrograph in a natural watershed. It was found that the direct numerical method applied to the homogeneous linear second order ordinary differential equation system is not suited to obtain the recession curve, and the case that the loss is generated in the partially penetrating stream can not be solved by the method of this study.

• Transactions of the Korean Society of Mechanical Engineers
• /
• 제12권3호
• /
• pp.607-621
• /
• 1988

The paper describes the incorporation of an algebraic stress model(ASM) of turbulence in to a semi-elliptic solution procedure for the prediction of turbulent flow in passage around a 180.deg. square sectioned bend. The numerical results are obtained from a finite-volume discretization with applications of QUICK scheme and full find grid system without PSL approximation. Results show that the better agreements in velocity profiles with experimental data than those from k, $\varepsilon$ equation model with wall function and PSL are obtained. Predictions of Reynolds stresses also show good agreements with the experimental data.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• 제32권5B호
• /
• pp.321-329
• /
• 2012

Two regular progressive wave trains, the directions of which are slightly different from each other, develop a honeycomb pattern of wave crests due to their nonlinear interaction. In the honeycomb pattern of wave crest, the nodal line area, which has very low wave energy, is formed. When the honeycomb pattern is developed near the beach area, rip current evolves through the nodal line area formed in the cross shore direction. In this study, to confirm that the formation of honeycomb pattern of waves near the beach area is a dominant mechanism of rip current occurred at Haeundae beach, we performed a numerical simulation of nearshore circulation at Haeundae beach under an unidirectional and monochromatic wave condition by using a nonlinear Boussinesq equation model. As a result, wave refraction due to topographical characteristics (i.e., submerged shoal) of Haeundae gave rise to several wave trains propagating with slightly different directions toward the beach, and consequently rip currents well developed through the nodal line area of honeycomb patterns of wave crest. In addition, we found that a narrow-banded spectral wave condition (i.e., a swell spectrum) increases more likelihood of rip current than a broad-banded spectral wave condtion based on the simulations employing various wave spectra with an equivalent wave height and period.

• Journal of Korea Water Resources Association
• /
• 제45권1호
• /
• pp.39-52
• /
• 2012

Surface-subsurface interactions are an intrinsic component of the hydrologic response within a watershed. In general, these interactions are considered to be one of the most difficult areas of the discipline, particularly for the modeler who intends simulate the dynamic relations between these two major domains of the hydrological cycle. In essence, one major complexity is the spatial and temporal variations in the dynamically interacting system behavior. The proper simulation of these variations requires the need for providing an appropriate coupling mechanism between the surface and subsurface components of the system. In this study, an approach for modelling surface-subsurface flow and transport in a fully intergrated way is presented. The model uses the 2-dimensional diffusion wave equation for sheet surface water flow, and the Boussinesq equation with the Darcy's law and Dupuit-Forchheimer's assumption for variably saturated subsurface water flow. The coupled system of equations governing surface and subsurface flows is discretized using the finite volume method with central differencing in space and the Crank-Nicolson method in time. The interactions between surface and subsurface flows are considered mass balance based on the continuity conditions of pressure head and exchange flux. The major module consists of four sub-module (SUBFA, SFA, IA and NS module) is developed.