• Title/Summary/Keyword: zero upcrossing method

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Development of Wave by Wave Analysis Program using MATLAB (MATLAB을 이용한 개별파 분석 프로그램 개발)

  • Choi, Hyukjin;Jeong, Shin Taek;Cho, Hong Yeon;Ko, Dong Hui;Kang, Keum Seok
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.29 no.5
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    • pp.239-246
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    • 2017
  • In case of observing only wave height and period in the field, various wave characteristics are mainly calculated by wave by wave analysis method. In this paper, an wave by wave analysis program using MATLAB language is developed. It is possible to perform a function such as 1) correction for mean water level, 2) calculation for zero crossing time, 3) calculation for individual wave height, 4) time interval by using zero upcrossing and downcrossing method. The applicability of the developed program to the data of 0.2 second interval observed by using the WaveGuide Radar installed on HeMOSU-1 was examined. Tidal level variation removal and zero crossing time estimation were determined by linear or quadratic interpolation. It was judged that the Goda method was appropriate for calculating individual wave height, and the method proposed in this study seems to be improved through subsequent research. Due to the fineness of the sample, it can be seen that characteristics of representative waves are different from the results calculated by zero upcrossing and downcrossing method.

Behavior of Non-buoyant Round Jet under Waves (파랑수역에서 비부력 원형 제트의 거동)

  • Ryu, Yong-Uk;Lee, Jong-In;Kim, Young-Taek
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.19 no.6
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    • pp.596-605
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    • 2007
  • The behavior of a non-buoyant turbulent round jet discharging horizontally was investigated experimentally. The instantaneous velocity field of the jet was obtained using the particle image velocimetry (PIV) method and used to calculate the mean velocity field by phase-averaging. This study tested regular waves with a relatively small wave height for a wavy environmental flow. The centerline and cross-sectional velocity profiles were reported to demonstrate the effect of the waves on the jet diffusion in respect of wave height and wave phase. The wave phase effect was studied for three phases: zero-upcrossing point, zero-downcrossing point, trough. From the results, it is found that the centerline velocity decreases and width of the cross-sectional profile increases as the wave height increases. In addition, the self-similarity of the cross-sectional profile appears to break down although the width of each case along the axial distance does not vary significantly. The phase effect is found to be relatively small compared to the wave height effect.