微尺度滑动平均方法计算海浪谱奇阶矩的公式
An equation for odd order spectral moments using partial averaging approach
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摘要: Glazman提出了一种计算海浪谱高阶谱矩的微尺度平均方法,但是,他利用随机过程理论导出的计算偶阶矩的公式和参照偶阶矩结论定义的奇阶矩计算公式之间存在着内在的不一致性.本文在Glazman工作的基础上根据随机过程理论推导了“微尺度平均方法”计算奇阶谱矩的公式,纠正了他的错误.上述结论随即应用于讨论破碎对波面水质点水平速度分布的影响.通过破碎的加速度判据考虑了破碎对速度分布的限制,给出了未破碎波面上水质点水平速度的的统计分布的初步结果.该分布取决于谱宽度参数及白浪覆盖率的大小,当白浪覆盖率较大时明显偏离正态分布.Abstract: A partial averaging approach used to evaluate high-order moments of wave spectra was developed by Glazman.He derived out a general equation to estimate even order moments from the known spectra and defined another one for odd order which is found to be inconsistent with the essence of the partial averaging.An alternative equation for odd order moments is got strictly from random process theory based on Glazman's partial averaging idea.The new equation is then employed in the study of the statistical distribution of horizontal velocities of the water particles on the unbroken sea surface.The effect of the occurrence of wave breaking on the statistical distribution of water particle velocities is considered through the wave breaking criterion about downward acceleration.It is found that this distribution deviates from Gaussian and is asymmetric about zero vertical velocity,further,it depends on two parameters,one of which is the spectral width εu,the other is the combination βg √M4 which is related to whitecap coverage.
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Key words:
- sea wave /
- spectral moment /
- horizontal velocity /
- vertical acceleration /
- wave breaking
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