• Title/Summary/Keyword: Wave maker

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Investigation of Characteristics of Waves Generated in Two-Dimensional Wave Channel (2차원 조파수조에서의 파 생성 특성 조사)

  • Ahn, Jae-Youl;Choi, Jung-Kyu;Kim, Hyoung-Tae
    • Journal of Ocean Engineering and Technology
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    • v.27 no.4
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    • pp.68-75
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    • 2013
  • This paper investigates the characteristics of waves generated by a flap-type wave maker in a two-dimensional wave channel. Measurements are carried out for various water depths, wave heights, periods, and lengths capacitance-type wave height gages. The experimental results are shown to satisfy the dispersion relation of the linear wave theory. For waves with a small height and long period, the wave profiles agree well with those of the linear wave theory. However, as the wave height and period become higher and shorter, respectively, it is shown that the wave profiles measured in the present experiments are different from the linear wave profiles, and the measured wave heights are smaller than the target wave heights, which may be due to the non-linearity of the waves. As the wave progresses toward the channel end, the wave height gradually decreases. This reduction in the wave height along the wave channel is explained by the wave energy dissipation due to the friction of the side walls of the channel. The performance of the wave absorber in the channel is found to be acceptable from the results of the wave reflection tests.

Visualization Study of Wave Generation in Short-Distance Wave Maker (소형 조파기 내의 조파생성에 대한 가시화연구)

  • Jung, Eui-Chul;Yuan, Zhen-Zhong;Lim, Hee-Chang
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.37 no.3
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    • pp.293-300
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    • 2013
  • This study used a water tank and wave maker to generate conditions similar to the real ocean environment. Given that the waves were properly generated in the water tank, a precise analysis indicated the quantitative value of the wave force acting on a body. A high-speed camera and wave-level gauge were used to measure the temporal wave motion and period. A series of artificial water waves were successfully generated using three different wave periods and amplitudes. Each of the waves captured by a high-speed camera was sinusoidal and did not maintain its shape properly without a wave absorber, but it was substantially improved and well shaped when the wave absorber was installed.

An Experimental Study on Development of Wave Absorber (소파장치 개발에 관한 실험적 연구)

  • 이희성;박준수;권순홍
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2000.04a
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    • pp.210-214
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    • 2000
  • This paper proposes a new wave absorber made of flexible net structures. The motivation of this research is that the wave absorbers which already invented are not effective in small wave flume. The proposed new wave absorber demonstrated its efficiency when used in small-length wave flume.

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Directional Wave Generation in the Navier-Stokes Equations Using the Internal Wave Maker (Navier-Stokes 방정식 모형의 경사지게 입사하는 파랑 내부조파)

  • Ha, Tae-Min;NamGung, Don;Cho, Yong-Sik
    • Journal of Korea Water Resources Association
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    • v.45 no.6
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    • pp.545-555
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    • 2012
  • A numerical modeling has become increasingly popular and more important to the study of water waves with a rapid advancement of computer technology. However, different types of problems are induced during simulating wave motion. One of the key problems is re-reflection to a computation domain at the incident boundary. The internal wave generating-absorbing boundary conditions have been commonly used in numerical wave models to prevent re-reflection. For the Navier-Stokes equations model, the internal wave maker using a mass source function of the continuity equation has been used to generate various types of waves. Nonetheless, almost every numerical experiment is performed in two dimensions and only a few tests have been expanded to three dimensions. More recently, a momentum source function of the Boussinesq equations is applied to generate essentially directional waves in the three dimensional Navier-Stokes equations model. In this study, the internal wave maker using a momentum source function is employed to generate targeted linear waves in the three-dimensional LES model.

An Analytical Study of Regular Waves Generated by Bottom Wave Makers in a 3-Dimensional Wave Basin (3차원 조파수조에서 바닥 조파장치에 의해 재현된 규칙파에 대한 해석적 연구)

  • Jung, Jae-Sang;Lee, Changhoon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.34 no.4
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    • pp.93-99
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    • 2022
  • Analytical solutions for regular waves generated by bottom wave makers in a 3-dimensional wave basin were derived in this study. Bottom wave makers which have triangular, rectangular and combination of two shapes were adopted. The 3-dimensional velocity potential was derived based on the linear wave theory with the bottom moving boundary condition, kinematic and dynamic free surface boundary conditions in a wave basin. Then, analytical solutions of 3-dimensional particle velocities and free surface displacement were derived from the velocity potential. The solutions showed physically valid results for regular waves generated by bottom wave makers in a wave basin. The analytical solution for obliquely propagating wave generation from bottom wave maker which works like a snake was also derived. Numerical results of the solution agree well with theoretically predicted results.

A Study on the Wave Generating Characteristics of the Multi-directional Irregular Wave Basin (다방향불규칙파 조파수조의 조파특성에 관한 연구)

  • SOHN Byung-Kyu;RYU Cheong-Ro
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.34 no.6
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    • pp.705-712
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    • 2001
  • It is of great importance to represent the directional ocean waves in a laboratory basin for hydraulic model tests. The directional ocean waves can be expressed as a linear superposition of a large number of component waves with different frequencies and propagating directions. The aim of the study is to check the wave generating characteristics by serpent-type wave generating system in PKNU (Pukyong National University) which is composed of 10 piston-type wave generators. In the experiment, spatial variation of irregular wave heights and propagating angles are measured in the multi-directional wave maker basin. Target wave directional spectrum is reproduced in the area of multi-directional wave maker basin. The directional spreading of the generated waves varied spacially in the basin. They differed from target spectrum as the measurement point becomes far from the center line normal to the generator face, The effective generation area where that target can be reproduced is limited to the triangular area attached the generator face. According to the results, it is emphasized that the effective experiment area in the basin considered wave generator characteristics should be determined in consideration of experimental conditions including structural shapes, water depth, wave directionality etc.

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On th Towing Tank of Inha University (인하대학교(仁河大學校) 선형시험수조(船型試驗水槽)에 관(關)하여)

  • K.J.,Cho;C.H.,Ihn;S.W.,Hong;R.S.,Park
    • Bulletin of the Society of Naval Architects of Korea
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    • v.10 no.2
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    • pp.29-37
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    • 1973
  • Since 1967 the Towing Tank of Inha University has been planed constracted and was completed 1971. The size of the tank is 79m length, 5m width 3m depth. At one end of the tank, 18kw wave maker is installed which can produce regular and irregular waves, max. 6m length 40cm height. The towing carriage is driven by four 2.2kw motor and reuglated by electronic speed regulator, and it's max. towing speed is 2.5m/sec, resistance dynamometer and some other instruments including clamp, towing guide etc. are designed and made by us. Here under, the authors wish to give some details of facilities and calibrated performance of the towing carriage, wave maker and resistance measuring system.

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Numerical Simulation of Solitary Wave Run-up with an Internal Wave-Maker of Navier-Stokes Equations Model (내부조파기법을 활용한 Navier-Stokes 방정식 모형의 고립파 처오름 수치모의)

  • Ha, Tae-Min;Kim, Hyung-Jun;Cho, Yong-Sik
    • Journal of Korea Water Resources Association
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    • v.43 no.9
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    • pp.801-811
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    • 2010
  • A three-dimensional numerical model called NEWTANK is employed to investigate solitary wave run-up with an internal wave-maker on a steep slope. The numerical model solves the spatially averaged Navier-Stokes equations for two-phase flows. The LES (large-eddy-simulation) approach is adopted to model the turbulence effect by using the Smagorinsky SGS (sub-grid scale) closure model. A two-step projection method is adopted in numerical solutions, aided by the Bi-CGSTAB (Bi-Conjugate Gradient Stabilized) method to solve the pressure Poisson equation for the filtered pressure field. The second-order accurate VOF (volume-of-fluid) method is used to track the distorted and broken free surface. A solitary wave is first internally generated and propagated over a constant water depth in the three-dimensional domain. Numerically predicted results are compared with analytical solutions and numerical errors are analyzed in detail. The model is then applied to study solitary wave run-up on a steep slope and the obtained results are compared with available laboratory measurements.

Seakeeping Study of a Container Ship in Regular Waves (콘테이너선의 파랑중 내항성 연구)

  • Yang, Seung-Il;Hong, Seok-Won;Lee, Sang-Mu
    • 한국기계연구소 소보
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    • s.9
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    • pp.193-208
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    • 1982
  • Flap type wave-maker, wave absorber, motion measuring equipment and related instruments were newly installed at Ship Experimental Towing Tank, Ship Research Station, KIMM. The model tests in regular head and following waves were successfully carried out and the motion and wave loads in regular and long crested irregular waves were calculated for a container ship model which was adopted as the hull form for the comparative calculations of the ITTC Seakeeping Committee. The results of model tests show good agreement with calculated results and the latter are generally in good agreement with the results of the comparative calculations.

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Visualization Study of the Floating Body Behavior in a Short-Distance Wave Maker (소형 조파기 내에서 부유체 거동에 대한 가시화연구)

  • Kim, Se-Young;Lim, Hee-Chang
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.5
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    • pp.381-388
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    • 2014
  • Our aim was to simulate ocean waves in a small-size wave flume and observe the motion of a cylindrical floating body placed in an offshore environment. To precisely visualize the oscillation of the body, a set of light-emitting diode illuminators and high-speed charge-coupled device camera were installed in the flume. Spectral analysis was performed of the movement of the floating body. The wave generator and absorbers worked well to simulate stable regular waves. As the period of the oncoming waves changed, the movement of the floating body substantially differed when tethered to a tension-leg mooring cable. In particular, when connected to the tension-leg mooring cable, the natural frequency of the floating body suddenly appeared at 0.391 Hz as the wave period was increased.