On surface gravity waves crossing weak current jets
On surface gravity waves crossing weak current jets
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表面重力波穿过弱流射流
DOI：
10.1017/s0022112083003365
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发表时间：
1983
影响因子：
3.7
通讯作者：
Jerome A. Smith
中科院分区：
文献类型：
--
作者：
Jerome A. Smith
对于宽而光滑的射流，已经描述了横跨水流射流的波幅和陡度的变化。在这里，狭窄的射流模拟的礼帽图案，线性波的近似解，根据守恒波的作用和垂直平均。结果与宽余弦形喷气式飞机的结果非常一致（参见。McKee 1975）。对于射流宽度小于约三分之一的波长，有很小的变化幅度，WKB分析预测的增强被抑制，由于从喷流的远侧反射的干扰。对于与cos 2 θ相差不大的方向谱，由于近侧反射排除了掠射波分量，所有尺度喷流的中部附近都会出现一些抑制;这种抑制对于波长宽度大于1的喷流可能是显著的。对于单色波，由于干扰，最大振幅出现在喷流之外的某个距离处;净反射似乎具有沿近焦散线约1/4周期的正相移沿着。
Variations in wave amplitude and steepness across current jets have been described for broad smooth-sided jets. Here, narrow jets are modelled by a top-hat pattern; an approximate solution is found for linear waves, based on conservation of wave action and vertical averaging. The results join remarkably well to those for a broad cosine-shaped jet (cf. McKee 1975). For jet widths less than about a third of a wavelength, there is little change in amplitude; the enhancement predicted by a WKB analysis is suppressed owing to interference with reflections from the far side of the jet. For directional spectra not too different from cos2 θ, some suppression occurs near the middle of jets of all scales, owing to exclusion of the glancing wave components by reflection from the near side; this suppression can be significant for jets more than a wavelength wide. For monochromatic waves, maximum amplitudes occur some distance outside the jet owing to interference; the net reflection appears to have a positive phase shift along the near caustic of about ¼ cycle.