• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3B
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• pp.305-308
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• 2011

In this study, generation methods of 3-D multi-directional random wave are examined using the fully non-linear numerical model with non-reflected wave generation system (LES-WASS-3D). Directional distribution functions obtained by EMLM method are compared for multidirectional random waves generated by various generation methods. As a results, it is revealed that multi-directional wave field can be simulated using LES-WASS-3D.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1995.10a
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• pp.85-90
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• 1995

수조에서 조파기로 규칙파와 불규픽파를 발생하는 실험은 오래전부터 수행되었고, 최근에는 이를 수치계산으로 검증하려는 노력이 이루어지고 있다. 본 논문에서는 2차원 수조에서 조파판의 작동을 적절히 조절하여 임의의 지점에 plunger 형 쇄파를 발생시키고, 수치계산으로 이를 확인한 내용을 담았다. 쇄파를 만드는 연구는 Chan(1988)이 조화함수를 합성시키는 기법으로 실험을 수행한 바가 있고, Dommermuth 등(1988)이 이를 수치적으로 검증하였다. (중략)

• Journal of the Society of Naval Architects of Korea
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• v.38 no.2
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• pp.1-9
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• 2001

Based on the linear potential theory with the side wall reflection. the directional spectrum waves are numerically simulated by a source distribution method and these together with long-crested irregular waves are also generated at the towing tank of Pusan National University by considering the transfer function of the wave maker obtained from the regular waves. In the numerical simulation, the characteristics of the directional spreading function are investigated by changing the breadth of the wave-maker unit. the width of the towing tank and the wave period. In the experimental generation, the statistical properties and the power spectrums of the long-crested irregular and directional waves are compared along the towing tank length. The directional spreading functions are also investigated at various positions in the tank.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.6
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• pp.401-406
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• 2011

In this study, generation methods of oblique incident wave are newly proposed and examined using the fully non-linear numerical model with non-reflected wave generation system(LES-WASS-3D). In order to verify, free surface elevation and horizontal velocities are compared with $3^{rd}$ -order Stokes wave theory in 3-D oblique incident wave field. As a results, it is revealed that the numerical results by newly proposed technique are in good agreement with the theory.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.805-817
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• 2016

This study considered the existing approximation theories of solitary wave for stable generation of it with different waveforms in a hydraulic/numerical wave tank for coping with the tsunami. Based on the approximation theory equations, two methods were proposed to estimate various waveforms of solitary wave. They estimate different waveforms and flow rates by applying waveform distribution factor and virtual depth factor with the original approximate expressions of solitary wave. Newly proposed estimation methods of solitary wave were applied in the wave generation of hydraulic/numerical wave tank. In the result, it was able to estimate the positional information signal of wave generator in the hydraulic wave tank and to find that the signal was very similar to an input signal of existing hydraulic model experiment. The waveform and velocity of solitary wave was applied to the numerical wave tank in order to generate wave, which enabled generate waveform of tsunami that was not reproduced with existing solitary wave approximation theory and found that the result had high conformity with existing experiment result. Therefore, it was able to validate and verify the two proposed estimation methods to generate stable tsunami in the hydraulic/numerical wave tank.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1993.07a
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• pp.51-54
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• 1993

수조안 주 실험구간에서의 유황이 주로 파랑에 의해서 영향을 받는 경우에는 실험결과의 정확도는 바로 사용된 조파기의 성능에 의해서 좌우된다. 컴퓨터를 이용한 조파기 제어시스템을 구축하기 위해서는 특정 조파판 운동에 대한 조파판에서의 수면변화 양상을 정확히 예측할 필요가 있다. 본 연구에서는 복소수 해석을 통하여 조파판 전달함수를 재구성하였으며 시간영역에서 전달함수를 개별적으로 구현할 수 있는 수치 필터를 제시한다. (중략)

• Journal of Navigation and Port Research
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• v.46 no.6
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• pp.471-482
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• 2022

This study aims to investigate the characteristics of wave generation in a deep ocean engineering basin and to develop a meta-model of the transfer function of the wavemaker that reflects the geometric characteristics of the deep ocean engineering basin. To this end, the two-dimensional frequency domain boundary element method was applied to achieve an efficient analysis that reflects the geometric characteristics of the deep ocean engineering basin. The developed numerical method was validated through comparison with the analytical solution. Numerical analyses were conducted for the boundary value problem of the wavemaker according to various periods and the positions of the movable bottom. The numerical results were used to investigate the effect of the geometric characteristics of the deep ocean engineering basin on the transfer function of the wavemaker, and the effect of depth on wave generation was checked by changing the position of the movable bottom. To efficiently utilize the various results of the boundary element method, a meta-model, an approximate model of the transfer function of the wave maker, was developed using a thin plate spline interpolation model. The validity of the developed meta-model was confirmed through a comparison of the results of the model tests.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.2
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• pp.111-117
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• 2012

Oscillating water column is the most widely used ocean energy converting systems all over the world. The operating performance is influenced by the efficiencies of the two converting stages in the OWC chamber-turbine integrated system. In order to consider the effects of the turbine, the orifice model are carried out. The VOF based Numerical Wave Tank (NWT) is utilized to simulate the water column oscillation inside the chamber and the results are compared with corresponding experimental data. This paper reviews the state of the art in interaction among wave elevation inside the chamber and air flow rate in the duct, which are considered the turbine effects. Effects of incident wave conditions and several shape parameters on the operating performance of OWC chamber are investigated numerically. The effects of the impulse turbine on the integrated system and interaction among the wave elevation, pressure and air flow velocities variations are investigated.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.1
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• pp.12-17
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• 2010

Oscillating Water Column (OWC) device has been widely employed in the wave energy conversion. Wave Focusing Device (WFD) is proposed to be helpful for improving the operating performance of OWC chamber. In the present paper, a Numerical Wave Tank (NWT) using two-phase VOF model is utilized to simulate the generation and propagation of incident regular waves, water column oscillation inside the chamber. The NWT consists of the continuity equation, Reynolds-averaged Navier-Stokes equations and two-phase VOF functions. The standard k- turbulence model, the finite volume method, NITA-PISO algorithm and dynamic mesh technique are employed. Effects of WFD on the operating performance of OWC chamber are investigated numerically.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.2
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• pp.91-98
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• 2010

The water elevation inside the air chamber and bi-directional air flow in the duct of Oscillating Water Column wave energy converter is one of the most important factors to evaluate the operating performance. The numerical wave tank based on the commercial software Fluent 6.2 in the present paper is employed to generate the incident waves. The numerical wave tank consists of the continuity equations, the Reynolds-averaged Navier-Stokes equations and the two-phase VOF function. The oscillating amplitude of water column in the chamber and bi-directional air flow in the duct installed on the top of the chamber are calculated, and compared with experimental data to verify the validation of the present NWT. The nozzle effects of the chamber-duct system on the relative amplitudes of the inner free water surface and air flow rate in the duct are investigated.