| 摘要: |
| 海浪的波谱特征分析对认识海浪有重要的意义，因为海浪谱反映了海浪的结构成分。这对海工建筑、海洋运输、船舶制造、海浪预报和海浪模拟等均有重要的实用意义。
波群是伴随海浪经常出现的一种自然现象，且经常伴随大浪的出现而出现。实践证明，波群具有极大的破坏力，其破坏性远比单个波大得多，它是海浪破坏海工建筑物的重要因子，许多防波堤的破坏并非是由单个波的作用，而是由相继出现的几个大波(波群)作用的结果。早先，人们对波群这种习见的现象研究甚少。自1974年葡萄牙锡尼斯港深水防波堤的破坏之后，对波群的研究才日益受到重视。
对波群的研究目前多采用包络方法、马尔科夫链方法和波能过程线法。波群研究的主要内容是波群的统计特征(如波群链长统计)；另外，波群的模拟也是重要的研究内容之一。目前用包络方法研究波群比较普遍，且有不少研究成果。徐德伦等(2001)综述了这方面的研究进展及结果，文圣常等(1984)也进行了详尽的讨论。
以往的研究大都是研究波群的统计特征，如合田良实(1976)、 Ewing(1973)、Rye(1974)。而针对地域性的波浪，我国学者也只是以包络方法为基础讨论了不同地域海浪波群的统计特征(常德馥，1987；葛明达，1986；范顺庭，1998)。就波群本身的结构特征而言，即波群的波谱分析特征以往的研究涉及尚少。作者拟借助于谱分析方法，对带有典型波群的实测的海浪记录来分析海浪波群的波谱结构，进而借此对海浪波群的结构特征进行深入探讨。 |
| 关键词: 海浪 波群 波谱结构 |
| DOI： |
| 分类号: |
| 基金项目:中国科学院海洋研究所调查研究报告第4566号。国家自然科学基金40076005和中国科学院知识创新工程项目(KZCX 2-202)资助。 |
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| Analysis of Characteristics of Wave Group Spectrum |
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YIN Baoshu, WU Shuping, FAN Shunting, WANG Tao, HOU Yijun, CHENG Minghua, YANG Dezhou
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Institute of Oceanology, The Chinese Academy of Sciences
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| Abstract: |
| Wave groups as natural phenomenon often accompanying sea waves have enormous destructive power. So, studies on them have aroused keen interest, especially in the ocean engineering community. Most past studies mainly focused on their statistical properties, rarely on their structural features. In this work, a dataset on typical wave groups was chosen to analyze the characteristics of wave group spectra by the gradual reduction of sampling numbers, using Fast Fourier Transform (FFT) and Maximum Entropy Method (MEM). The results indicated that the wave group spectrum obviously differed from common wave spectrum. The frequency range of wave group spectrum becomes narrow obviously and the peak value of its spectrum becomes large obviously. The whole spectral shape is similar to δ function. Also, when the many component waves the wave groups contain gradually reduce to one large component wave, the analysis results showed the features of two peak spectrum. The spectra of typical wave groups consist of two frequency components with approximately the same frequencies but different amplitudes. That is to say, the typical wave group is the superposition resultant of two train waves whose frequencies are nearly the same and amplitudes are different, just like the "BEAT" in physics-which is the resultant of two simple harmonic motions with identical motion direction, different amplitudes and periods.
This study demonstrated that wave group spectrum is of the shape of δ function, which has important significance for engineering design and deserve our great attention. |
| Key words: Sea waves wave group是 |
