Transcript wave_statics

NRCEST
國立交通大學土木工程學系
中華民國102年3月28日
Reference
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methods
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Significant wave representation
Individual wave H1>H2>H3…
Brestchneider (1968)
H1/3:前1/3大之個別波波高平均值 (significant wave, 示性波)
T1/3:相對於大小排序波高之週期平均值
Neir et al. (2003)
T1/3:T1>T2>T3…週期仿照示性波高前1/3大之平均值週期
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Statistical properties
Rayleigh distribution
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Representative wave height
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Representative wave height
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Statistical theory for irregular waves
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Rayleigh distribution for wave height
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Rayleigh distribution for wave height
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Rayleigh distribution for wave height
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Rayleigh distribution for wave height
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1/Nth Waves for Rayleigh distribution
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1/Nth Waves for Rayleigh distribution
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1/Nth Waves for Rayleigh distribution
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1/Nth Waves for other distributions
表 2.3-1 計算 Weibull 及 Gauss 分布示性波之理論統計公式
分布函數
計算示性波公式
1
 [(ln 3)  ] 
Weibull 分布
Normal 分布
3
2
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e
 x p 
 
 2




2

3

1
( , ln 3)

 xp   
3

Erfc
2
2 

Regular wave
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Irregular wave
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Frequency spectrum of irregular waves
Fourier transform
(Fast FT)
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Frequency spectrum of irregular waves
Brestchneider (1968)
Wallops spectrum by Hwung et al . (1981)
Goda (1988)
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Frequency spectra of irregular waves
JONSWAP (1973)
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Directional Spectrum of sea waves
G(θ) : directional distribution of energy spectrum
S(f) : energy (power) spectrum
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Directional Spectra of sea waves
Mitsuyasu (1975)
Smax: Spreading parameter
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Directional Spectra of sea waves
Smax=20
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Relationship between spectra and wave height
Zeroth moment of spectrum
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Relationship between spectra and wave height
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Relationship between spectra and wave period
Zeroth and second moments of spectrum
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Spectra of sea waves-Example I
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Example I
Directional spectrum
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Example-I
sample average of
sixteen directional spectra
directional spectra of
in-site buoy measurements
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Example-I
Power spectrum
directional spreading function
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Example-II
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Example-II
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Example-II
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