• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.14 no.2
• /
• pp.171-181
• /
• 2002

Among various numerical methods of wave transformations including wave breaking by structure, models using VOF(Volume Of Fluid) method to trace free surface are getting into the spotlight recently. In order to analyze wave transformations and velocity of the wave fields due to the permeable submerged breakwater(PSB), This study applied VOF method to the two-dimensional wave channel installed line-source to generate waves and added dissipation zone to offer a non-reflective boundary. Hydraulic experiments was performed to obtain the application of two-dimensional numerical wave channel. The results of numerical experiments using the two-dimensional wave channel agree well with the experimental data. It was shown that vortices are formed behind the PSB, and in case of the 2-rowed PSB they also are occurred in between PSBs, strongly non-linear waves are developed on the crown of the PSB, and the direction of velocities in porous media is determined by the shape of free surface.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.19 no.6
• /
• pp.557-564
• /
• 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.

• Journal of Korea Water Resources Association
• /
• v.54 no.1
• /
• pp.39-48
• /
• 2021

The experiment of rip current at successive ends of breaking wave crests was conducted in a laboratory wave basin, and its time-varying evolution according to incident wave durations was observed by using ortho-rectified images. The experiment utilized the generation of a quasi nodal line of the honeycomb-pattern waves (i.e., intersecting wave trains) formed by out-of-phase motion of two piston-type wave makers arranged in the transverse direction, instead of the original honeycomb pattern waves which are generated when two wave trains propagate with slightly different wave directions. The particle moving distance and velocity caused by the rip current were measured by using the particle tracking technique. As a result, the rip current was survived for a while even without incident waves after its generation due to several successive ends of wave crests, and it moved the particles further out to sea.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.19 no.4
• /
• pp.355-360
• /
• 2007

The process of the nonlinear shallow water wave transformation in a basin of a constant depth is studied. Characteristics of the first breaking of the wave are analyzed in details. The Fourier spectrum and steepness of the nonlinear wave are calculated. It is shown that the spectral amplitudes can be expressed using the wave front steepness, which allows the practical estimations.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.18 no.2
• /
• pp.166-177
• /
• 2006

The accuracy impact of using high-order Boussinesq-type model as compared to the typical order model is examined in this paper. The multi-layer model developed by Lynett and Liu(2004a) is used for simulating of wave breaking over a shelf region. The nonlinearity of the waves tested, ${k_0}{A_0}$, ranges from 0.029 to 0.180. The overall agreement between the two-layer model and the hydraulic experiments are quite good. The one-layer model overshoals the wave near the breakpoint, while the two-layer model shoals at a rate more consistent with the experimental data.

• Journal of Navigation and Port Research
• /
• v.28 no.8
• /
• pp.753-757
• /
• 2004

The free-surface flow is simulated to make clear the viscous interaction of stem waves and the sub-breaking phenomena around a high speed vehicle. The Navier-Stokes equation is solved by a finite difference method where the body-fitted coordinate system, the wall function and the triple-grid system are invoked They are applied to study precisely on the stem flow of S-103 as to which extensive experimental data are available. Computations are extended to the submerged revolutional body. The numerical result shows that the gradient of M/Us is greatly influenced by the submerged depth And the stem wave is influenced by the separation due to the bow wave.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2004.08a
• /
• pp.217-225
• /
• 2004

Introduction of wave model, considered the effect of shoaling, refraction, diffraction, partial reflection, bottom friction, breaking at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster prevention problems. As waves move from deeper waters to shallow coastal waters, the fundamental wave parameters will change and the wave energy is redistributed along wave crests due to the depth variation, the presence of islands, coastal protection structures, irregularities of the enclosing shore boundaries, and other geological features. Moreover, waves undergo severe change inside the surf zone where wave breaking occurs and in the regions where reflected waves from coastline and structural boundaries interact with the incident waves. Therefore, the application of mild-slope equation model in this field would help for understanding of wave transformation mechanism where many other models could not deal with up to now. The purpose of this study is to form a extended mild-slope equation wave model and make comparison and analysis on variation of harbor responses in the vicinities of Ulsan Harbor and Ulsan New Port, etc. due to construction of New Port in Ulsan Bay. This type of trial might be a milestone for port development in macro scale, where the induced impact analysis in the existing port due to the development could be easily neglected.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.32 no.6
• /
• pp.411-419
• /
• 2020

The experiment of unsteady rip current generated at the successive ends of breaking wave crests of honeycomb pattern waves was conducted in a laboratory wave basin, and its time-varying evolution was observed by using ortho-rectified images. The present experiment utilized the generation of a quasi nodal line of the honeycomb-pattern waves formed by out-of-phase motion of two piston-type wavemakers arranged in the transverse direction, instead of the original honeycomb pattern waves which are generated when two wave trains propagate with slightly different wave directions. The velocities of rip current were measured by using the LSPIV (Large-Scale Particle Image Velocimetry) technique. As a result, the unsteady rip current was generated between successive ends of wave crests, and evolved with its shear fluctuations in this experiment. Also, the time series of LSPIV velocity of the unsteady rip current showd its short component due to waves and its long component due to wave-induced currents.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.2
• /
• pp.148-156
• /
• 2008

WAM(WAve Model), deep water wave model has been extended to the region of shallow water, incorporating wave breaking, and triad wave interaction. To verify this model, two numerical simulations for hydraulic experiments of Chawla et al.(1998) and Beji and Battjes(1993) are performed. The computed results show good agreements with measured ones. To identify its applicability to real sea, it is applied to storm wave modelling for typhoon Maemi. Numerical results compared with measured ones at Geoje, Busan and Ulsan show reasonable wave height estimations.

• Journal of Ocean Engineering and Technology
• /
• v.19 no.3
• /
• pp.18-24
• /
• 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.