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題名 | 斷面水槽中不規則波統計特性的探討=Statistical Properties of Laboratory Simulated Random Waves |
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作者 | 尹彰; 林炤圭; | 書刊名 | 中國土木水利工程學刊 |
卷期 | 10:4 1998.12[民87.12] |
頁次 | 頁759-771 |
分類號 | 443 |
關鍵詞 | 機械波; JONSWAP頻譜; 波高分佈; 水面分佈; Mechanical waves; JONSWAP spectrum; Wave height distribution; Surface distribution; |
語文 | 中文(Chinese) |
中文摘要 | 利用一個全長100m,寬、高各3m 的斷面水槽及電腦控制的不規則造波機,藉著 變換造波程式中 JONSWAP 頻譜裡「頂點提昇係數」值 (peak enhancement factor, γ ) 來探討頻譜寬度和不規則波統計特性之間的關係。 一共使用了 Rayleigh、Weibull 以及常 態等三種分佈模式來測試斷面水槽裡所得的波高機率分佈。並用常態、Gram-Charlier 級數 系列以及非線性 Stokes 波的模式來探討水面的機率分佈。測試的結果顯示;不論頻譜γ值 的大小, Rayleigh 等三種模式都可以用來描述所量測到的波高機率分佈。 其中又以 Rayleigh 及 Weibull 兩種模式的套配結果最好。隨γ值的增加 (頻譜變窄 ),非線性的影 響漸漸地顯現出來,水面機率分佈逐漸地偏離常態, 而變得趨向於 Gram-Charlier 級數系 列的分佈。另外,Huang 等人描述 Stokes 有限振幅波水面變化機率分佈的模式對γ值的敏 感度不大。在本文所用的實驗資料中,這個模式所得到的曲線和常態分佈的套配結果幾乎重 疊在一起而不易分辨。 |
英文摘要 | Irregular waves were generated mechanically in a large wave flume using the JONSWAP as target spectrum. Possible effects of spectral bandwidth on the statistical properties of wave height and surface distributions were studied through variations of the peak enhancement factor, γ, of the JONSWAP spectrum. Three models, namely the Gaussian, the Rayleigh and the Weibull, were used to fit wave height distributions. The normal, the Gram-Charlier type series expansions, and the model for finite amplitude Stokes waves were chosen as possible candidates for the distribution of surface elevations. The results indicate that, all the three models can be used to describe wave height distributions in the flume, with the Rayleigh and the Weibull being superior than the normal. With increasing values of the peak enhancement factor, the effect of nonlinearity become discernible, surface elevations are then better dscribed by the Gram-Charlier series model. In all cases studied, the curves resulting from the model of Huang et al. almost coalesce with the Gaussian, making both curves indistinguishable. |
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