Higher-harmonic focused-wave forces on a vertical cylinder
Higher-harmonic focused-wave forces on a vertical cylinder
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DOI：
10.1016/j.oceaneng.2009.02.009
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发表时间：
2009-06
影响因子：
5
通讯作者：
Yuxiang Ma;G. Dong;M. Perlin;Shu-xue Liu;J. Zang;Yiyang Sun
中科院分区：
文献类型：
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作者：
Yuxiang Ma;G. Dong;M. Perlin;Shu-xue Liu;J. Zang;Yiyang Sun
本文研究了波浪作用于垂直圆柱上的高次谐波力。在波浪水槽中进行了一系列的实验。利用尺度平均小波谱分析了实测波浪力的前六次谐波分量。应注意，由于聚焦（反常）波的瞬态性质，傅立叶分析将不提供与从本文使用的分析收集的信息等效的信息。具有非常陡峭波峰的实验结果显示在第四和第五谐波处的显著振幅。这些谐波的振幅与二次谐波的振幅相同，但比三次谐波的振幅大得多。基于小波的双相干被用来检测被测力的二次非线性。双相干谱揭示了四次和五次谐波显著振幅存在的主要数学原因：低次谐波分量与四次和五次谐波之间的相互作用更强，因此四次和五次谐波比三次谐波分量收集更多的能量。然而，对这一现象的物理解释仍然难以捉摸。
This paper considers higher-harmonic forces due to wave focusing on a vertical circular cylinder. A series of experiments has been conducted in a wave flume. The first six-harmonic components of the measured wave forces are analyzed using the scale-averaged wavelet spectrum. It is noted that due to the transient nature of focused (freak) waves, Fourier analysis would not provide equivalent information to that gleaned from the analyses used herein. The results for the experiments with very steep wave crests show significant amplitudes at the fourth and fifth harmonics. These harmonics exhibit amplitudes that are the same order as the second harmonic, but much larger than those of the third harmonic. The wavelet-based bicoherence is used to detect the quadratic nonlinearity of the measured forces. And the bicoherence spectra reveal the primary mathematical reason for the existence of the striking amplitudes of the fourth and fifth harmonics: the interaction between the lower-harmonic components couple more strongly with the fourth and fifth harmonics, thus the fourth and fifth harmonics glean more energy than those of the third-harmonic components. However, the physical explanation for this remains elusive.