• Title, Summary, Keyword: Incident wave

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Numerical Analysis of Four Circular Columns in Square Array and Wave Interaction (파랑과 정사각형 배열의 원형 기둥 구조물의 상호작용 수치해석)

  • Song, Seongjin;Park, Sunho
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.23 no.5
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    • pp.558-565
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    • 2017
  • Accurate prediction of wave-structure interactions is important in the safety and design cost effectiveness of fixed and floating offshore structures exposed to extreme environmental conditions. In this study, regular waves and circular column structure interactions for four circular columns in regular waves are analyzed. To simulate 3D two-phase flow, open source computational fluid dynamics libraries, called OpenFOAM, were used. When the four circular columns are arranged in a square array, the interactions according to the incident slopes of the regular waves are analyzed. The wave run-up in the circular column surface was compared according to the slope of the incident wave. It was confirmed that high amplitude waves are generated between the circular columns due to the interaction between the circular column and the incident wave. It is expected that this analytical result will be used as the basic data of the study on the air gap due to the interaction between the structure and incident wave.

On Generation Methods of Oblique Incidence Waves in Three-Dimensional Numerical Wave Tank with Non-Reflected System (3차원 무반사 수치파동수조에서 경사입사파의 조파기법 개발)

  • Hur, Dong-Soo;Lee, Woo-Dong
    • 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.

Passive Control of the Impulse Wave Using a Helical Vane (Helical Vane 을 이용한 펄스파의 피동제어)

  • Yang, Soo-Young;Lee, Dong-Hoon;Kim, Heuy-Dong;Setoguchi, Toshiaki
    • Proceedings of the KSME Conference
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    • pp.792-797
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    • 2003
  • A helical vane is applied to reduce the magnitude of the impulse wave discharged from the exit of a duct. A shock tube with an open end is used to investigate the effect of the helical vanes on the impulse wave magnitude. Four different types of helical vanes are installed into the low-pressure tube of shock tube. The magnitude of the incident shock wave is varied below 1.25, and the magnitude of impulse wave is measured using a pressure transducer mounted on a wedge probe. Instant images of the impulse wave are obtained by means of the Schlieren optical method. The present experimental results show that the helical vane considerably reduces the magnitude of the impulse wave and the vane effects are more remarkable for stronger incident shock wave.

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A Study of the Impulse Wave Discharged from a Perforated Pipe (다공관으로부터 방출되는 펄스파에 관한 연구)

  • Shin Hyun Dong;Kweon Yong Hun;Kim Heuy Dong
    • 한국가시화정보학회:학술대회논문집
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    • pp.95-98
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    • 2003
  • When a shock wave discharges from an open end of a duct, an impulse wave is generated outside the duct, causing serious noise and vibration problems. The magnitude of the impulse wave can be reduced by installing of a perforated duct. In the current study, the characteristics of the impulse wave discharged from the exit of a perforated duct are numerically investigated. A TVD (total variation diminishing) scheme is used to solve the unsteady, axisymmetric, compressible Euler equations. In computations, the porosity of a perforated pipe $(\sigma)$ and the Mach number of incident shock wave $(M_s)$ are varied in the range of $\sigma=0\~19\%\;and\;M_s=1.01\~1.50$, respectively. The results show that the directivity and magnitude of impulse wave strongly depend upon the Mach number of incident shock wave and the porosity of the perforated pipe. The present CFD results are in close agreement with experimental results.

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Submerged Porous Plate Wave Absorber

  • PARK W.T.;LEE S.H.;KEE S.T.
    • Journal of Ocean Engineering and Technology
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    • v.19 no.4
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    • pp.9-14
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    • 2005
  • In the present paper, the wave absorbing performance of the fully submerged horizontal porous plates has been investigated, numerically and experimentally. The submerged porous system is composed of multi-layered horizontal porous plates that are clamped at the vertical setwall, which are slightly inclined and placed vertically, in parallel, with spacing. The hydrodynamic interaction of incident waves with the rigid porous multi-layered plates was formulated within the context of linear wave-body interaction theory and Darcy's law. In order to validate the effectiveness of the present computing code, the numerical results were compared with the analytical and experimental results. It is found that triple horizontal porous plates with slight inclination, if properly tuned for wave energy dissipation against the standing waves in front of the vertical wall, can have high performances in reducing the reflected wave amplitudes against the incident waves over a wide range of wave frequency.

Experimental Comparison of the Wave Force on Crown Wall of Sloping Breakwater Armored with Tetrapods under Obliquely Incident Waves (경사입사 시 테트라포드로 피복된 경사제 상부구조물에 작용하는 파력 비교 실험)

  • Oh, Sang-Ho;Lee, Jooyeon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.32 no.3
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    • pp.161-169
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    • 2020
  • Physical experiments have been performed in a wave basin to investigate change of the wave loading on the crown wall under obliquely incident wave conditions. The measurement was carried out with wave incidence angle of 0, 15, 30 and 45°. The pressure transducers were placed on the front and bottom face of the crown wall to obtain horizontal and uplift force as well. It was found that both the horizontal and vertical force decreases with the incidence angle. Based on the analysis of the experimental data, a formula was suggested to estimate the reduction rate of horizontal and vertical forces under obliquely incident waves.

Numerical Analysis of Wave Deformation with Sea Bottom Variation(II) (해저지형 변화에 따른 파랑의 수치해석(II))

  • 김성덕;이성대
    • Water for future
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    • v.20 no.1
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    • pp.49-54
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    • 1987
  • A numerical analysis of the characteristics of wave reflection over rippled beds (sand bars) was carried out By Boundary Element Method(B.E.M) using linear elements. It is assumed that the incident wave is normal and oblique to the rippled beds and the wave may be and the escribed by two-dimensional linear theory. The accuracy of the computational scheme is investigated by comparing the laboratory data, the analytic measured results of the other researchers. The B.E.M results for the normal incident wave is held for the mechanism of the resonant Bragg reflection at the point where the wave length of the bottom undulation is one half the wave length of the surface wave.

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Submerged Membrane Breakwaters I: A Rahmen Type System Composed of Horizontal and Vertical Membranes

  • Kee, Sung-Tae
    • International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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    • v.5 no.1
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    • pp.14-21
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    • 2002
  • In the present paper, the hydrodynamic properties of a Rahmen-type, flexible, porous breakwater interacting with obliquely or normal- incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes, hinged at the side edges of a submerged horizontal membrane. The dual vertical membranes are extended downward and hinged at seabed. The effects of permeability, Rahmen-type membrane breakwater geometry, pre-tensions on membranes, relative dimensionless wave number, and incident wave headings are thoroughly examined.

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Inner harbour wave agitation using boussinesq wave model

  • Panigrahi, Jitendra K.;Padhy, C.P.;Murty, A.S.N.
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.1
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    • pp.70-86
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    • 2015
  • Short crested waves play an important role for planning and design of harbours. In this context a numerical simulation is carried out to evaluate wave tranquility inside a real harbour located in east coast of India. The annual offshore wave climate proximity to harbour site is established using Wave Model (WAM) hindcast wave data. The deep water waves are transformed to harbour front using a Near Shore spectral Wave model (NSW). A directional analysis is carried out to determine the probable incident wave directions towards the harbour. Most critical threshold wave height and wave period is chosen for normal operating conditions using exceedence probability analysis. Irregular random waves from various directions are generated confirming to Pierson Moskowitz spectrum at 20m water depth. Wave incident into inner harbor through harbor entrance is performed using Boussinesq Wave model (BW). Wave disturbance experienced inside the harbour and at various berths are analysed. The paper discusses the progresses took place in short wave modeling and it demonstrates application of wave climate for the evaluation of harbor tranquility using various types of wave models.

Runup and Reflection of Waves on Impermeable Slopes of Coastal Structures (불투수성 경사면에서 파의 처오름과 반사)

  • Lee, Cheol-Eung
    • Journal of Industrial Technology
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    • v.21 no.B
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    • pp.175-185
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    • 2001
  • A numerical model is represented to calculate the reflected waves, the runup of waves and the wave induced velocities on impermeable slopes for the normally incident wave trains of nonlinear monochromatic wave and solitary wave. The finite amplitude shallow water equations with the effects of bottom friction are solved numerically in time domain using an explicit dissipative Lax-Wendroff finite difference method. The numerical model is verified by comparisons with the other numerical results, the measured data and asymptotic results. It is found that the uprushing and downrushing of incident waves may be accurately predicted by the present numerical model. Therefore, the present numerical model can be applicable to swells as well as long waves.

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