• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.3
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• pp.440-447
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• 2012

Numerical model experiments of wave transformation due to the reclamation and the construction of breakwater in case of 50 years design wave were performed using time dependent mild slope equation included shoaling, refraction, diffraction, reflection and wave breaking. As waves propagate to the shore, wave height gradually diminishes by the bottom friction and wave breaking etc.. After the reclamation and the construction of 75 m length breakwater, wave height distributions in the lee of breakwater have the range of 29~128 cm. To make better the harbor tranquility the length of breakwater needs to extend more than 100 m. After the construction of breakwater, wave height in the lee of the structure was deduced over 80%.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.1 s.145
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• pp.96-102
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• 2006

In this study, an optimization routine with genetic algorithms is coupled for the selection of free variables for the production of a control signal for the motion of wave board in the numerical wave tank. An excitation function for the controlling of the wave board is formulated on basis of amplitude modulation for the generation of nonlinear wave packets. The found variables by the optimization serve for the determination of wave board motion both with the computation and with the experiment. The breaking criterion of the water waves is implemented as boundary condition for the optimization procedure. With the analysis of the time registration on the local position in the wave tank the optimization routine is accomplished until the given design wave with defined surface elevation is found. Water surface elevation and associated fields of velocity and pressure are numerically computed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.619-633
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• 1994

A wave deformation model for general purpose combined refraction, diffraction, and breaking is developed in the shallow water. A parabolic approximation equation considered a higher order diffraction term is derived from the previous mild slope equation. A wave energy dissipation term due to bottom friction and breaking is introduced from the turbulence model. The Crank-Nicoloson implicit scheme is used in the numerical calculation, then the solutions are compared with the various hydraulic experiment data in the circular, the elliptic shoal, and the surf zone. The wave height decay in the surf zone is sensitively affected by the incident wave steepness, and the wave height variation around the elliptic shoal is well explained by the non-linear dispersion relation and the wave energy dissipation term. The model is also applied to a field coastal area and reasonable results are obtained.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.3
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• pp.216-224
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• 2011

In This study develops a quasi-three dimensional numerical model of wave driven coastal currents with accounting the effects of the wave-current interaction and the surface rollers. In the wave model, the current effects on wave breaking and energy dissipation are taken into account as well as the wave diffraction effect. The surface roller associated with wave breaking was modeled based on a modification of the equations by Dally and Brown (1995) and Larson and Kraus (2002). Furthermore, the quasi-three dimensional model, which based on Navier-Stokes equations, was modified in association with the surface roller effect, and solved using frictional step method. The model was validated by data sets obtained during experiments on the Large Scale Sediment Transport Facility (LSTF) basin and the Hazaki Oceanographical Research Station (HORS). Then, a model test against detached breakwater was carried out to investigate the performance of the model around coastal structures. Finally, the model was applied to Akasaki port to verify the hydrodynamics around coastal structures. Good agreements between computations and measurements were obtained with regard to the cross-shore variation in waves and currents in nearshore and surf zone.

• Journal of Ocean Engineering and Technology
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• v.9 no.2
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• pp.149-155
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• 1995

This study is to investigate the dynamic pressure caused by breaking waves on a recurved offshore structure. A physical modelling was performed in a two-dimensional wave flume. The measuments from the physical modelling were compared with several known equations. The shock and secondary pressures were found to be dependent on water depth, breaking wave height and the size of the air pocket. The maximum pressure was recorded near the still water level and the secondary pressures near the recurved the recurved structure were found to be less than those experienced in a vertical offshore structure.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.1
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• pp.1-11
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• 1995

A numerical shallow water wave deformation model to solve unsteady mild slope equation was develope(1. The energy equation of Izumiya and Horikawa(1984) for wave breaking and bottom friction was incorporated to estimate more realistically energy damping resulted from wave breaking and reflection. A numerical scheme for variable grid spacings was also introduced to complement the defect of unsteady mild slope equation limiting the grid spacings. This model was tested and compared with the existing analytic solutions and physical modelings, and applied to a practical situation.

• International Journal of Naval Architecture and Ocean Engineering
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• v.1 no.1
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• pp.20-28
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• 2009

In thus paper we validate a numerical model for wave-structure interaction by comparing numerical results with laboratory data. The numerical model is based on the Navier-Stokes (N-S) equations for an incompressible fluid. The N-S equations are solved by a two-step projection finite volume scheme and the free surface displacements are tracked by the volume of fluid (VOF) method The numerical model is used to simulate solitary waves and their interaction with a group of slender vertical piles. Numerical results are compared with the laboratory data and very good agreement is observed for the time history of free surface displacement, fluid particle velocity and wave force. The agreement for dynamic pressure on the cylinder is less satisfactory, which is primarily caused by instrument errors.

• Journal of the Korean Society of Clothing and Textiles
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• v.36 no.6
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• pp.583-591
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• 2012

This study selected three model designs used for air injection type welding clothes designed for insulation purposes and analyzed the performance of each design. The bending characteristics were analyzed in order to identify the flexibility of the welded areas; subsequently, the seam breaking strength and water pressure resistance were analyzed to identify the bonding strength. In addition, two types of waterproof fabric, polyurethane (PU) coated 2 layer and PU laminated 2 layer fabrics, were used for a performance analysis, according to fabric processing specifications. The circle type showed the highest flexibility in the terms of bending characteristics that influence wearability and were followed by the wave and the straight type. In terms of breaking strength, the straight type showed the highest breaking strength, followed by the wave and the circle type. The water pressure resistance analysis found that the wave type was superior to the straight type in terms of water pressure resistance. The wave type is deemed to be a design type suitable for maximizing performance, provided that the issue of stabilization in the welding production process is addressed. Looking at the bending characteristics of waterproof fabric for each specification, the laminating waterproof cloth outperformed the coated waterproof cloth in terms of flexibility. However, in terms of seam breaking strength, the coated waterproof cloth outperformed the laminated cloth. In contrast, the water pressure resistance of the laminated waterproof fabric was found to be higher than the coated waterproof fabric, leading to the conclusion that the bonding strength of the laminated waterproof fabric is higher than that of the coated waterproof fabric based on the assumption of injecting air.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2009.10a
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• pp.164-167
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• 2009

• Journal of Mechanical Science and Technology
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• v.15 no.4
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• pp.465-472
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• 2001

A numerical study is carried out to clarify the characteristics of flow fields and breaking phenomena around a high speed catamaran hull advancing on calm water. Computations are carried out for Froude numbers between 0.2 and 1.0 and for ratios of the distance between hulls to the catamaran length varying between 0.2 and 0.5 for a mathematically defined Wigley hull. A Navier-Stokes solver which includes the nonlinearities of free surface conditions is employed. Computations are performed in a rectangular grid system based on the Marker & Cell method. For validation, present computation results are compared with existing experimental results. As an application, the results of the displacement catamaran are used for the breaking analysis.