On resonant triad interactions of acoustic-gravity waves
On resonant triad interactions of acoustic-gravity waves
复制标题
DOI：
10.1017/jfm.2015.721
复制
发表时间：
2016-02-01
影响因子：
3.7
通讯作者：
Akylas, T. R.
中科院分区：
文献类型：
--
作者：
Kadri, Usama;Akylas, T. R.
讨论了波浪扰动在均匀深度水中的传播，同时考虑了重力和压缩性效应。在线性理论中，自由表面（重力）波实际上与声（压缩）波解耦，因为水中的声速远远超过重力波的最大相速度。然而，这两种类型的波动可以通过共振三元组非线性相互作用交换能量。针对包含长波峰声模和两个相反传播的次谐波重力波的三元组来分析该场景。由于重力和声学长度尺度的差异，相互作用的时间尺度比标准共振三重轴的时间尺度长，并且适当的振幅演化方程除了通常的二次相互作用项外，还涉及某些三次项。尽管如此，单色波列仍然有可能形成精细调谐的三元组，使得重力波中最初的几乎所有能量都转移到声学模式。然而，这种耦合机制对于局部受限的波包来说效果要差得多。
The propagation of wave disturbances in water of uniform depth is discussed, accounting for both gravity and compressibility effects. In the linear theory, free-surface (gravity) waves are virtually decoupled from acoustic (compression) waves, because the speed of sound in water far exceeds the maximum phase speed of gravity waves. However, these two types of wave motion could exchange energy via resonant triad nonlinear interactions. This scenario is analysed for triads comprising a long-crested acoustic mode and two oppositely propagating subharmonic gravity waves. Owing to the disparity of the gravity and acoustic length scales, the interaction time scale is longer than that of a standard resonant triad, and the appropriate amplitude evolution equations, apart from the usual quadratic interaction terms, also involve certain cubic terms. Nevertheless, it is still possible for monochromatic wavetrains to form finely tuned triads, such that nearly all the energy initially in the gravity waves is transferred to the acoustic mode. This coupling mechanism, however, is far less effective for locally confined wavepackets.