论文标题
在有限宽度的内部重力波梁中，三合会共振不稳定性的长远视图
The long view of triadic resonance instability in finite-width internal gravity wave beams
论文作者
论文摘要
本文介绍了我们对由三合会共振不稳定性产生的有限宽度内部重力波束修改的研究。我们介绍了实验性和弱非线性建模，以检查这种不稳定性机制，其中主波梁产生了两个较低频率和较短长度尺度的次级波梁。通过多功能实验设置，我们研究了这种不稳定性如何在数百个浮力周期中发展。与先前的零维弱非线性理论的预测不同，我们发现三合会相互作用的饱和平衡态的方法不是单调的。相反，组成梁的幅度和结构继续调节而没有达到稳定的平衡。为了了解这种行为，我们开发了一种弱的非线性方法，以说明梁在缓慢的时间尺度和长距离上的振幅和结构的时空演化，并使用数值方案探索后果。通过这种方法，我们确定不稳定性的演变对系统的时空三合会配置非常敏感，以及观察到的调制的一部分如何归因于次级波梁的线性生长速率与下层主束内三联膜的有限生活时间之间的线性生长速率之间的竞争。
This paper presents our investigation into the modification of a finite-width internal gravity wave beam arising from triadic resonance instability. We present both experimental and weakly non-linear modelling to examine this instability mechanism, in which a primary wave beam generates two secondary wave beams of lower frequencies and shorter length scales. Through a versatile experimental set-up, we examine how this instability develops over hundreds of buoyancy periods. Unlike predictions from previous zero-dimensional weakly non-linear theory, we find that the approach to a saturated equilibrium state for the triadic interactions is not monotonic; rather, the amplitudes and structures of the constituent beams continue to modulate without ever reaching a steady equilibrium. To understand this behaviour we develop a weakly non-linear approach to account for the spatio-temporal evolution of the amplitudes and structures of the beams over slow time-scales and long distances, and explore the consequences using a numerical scheme. Through this approach, we establish that the evolution of the instability is remarkably sensitive to the spatio-temporal triadic configuration for the system and how part of the observed modulations can be attributed to a competition between the linear growth rate of the secondary wave beams and the finite residence time of the triadic perturbations within the underlying primary beam.
