论文标题
波驱动旋转湍流中的地球植物快捷方式：四次不稳定性
Shortcut to geostrophy in wave-driven rotating turbulence: the quartetic instability
论文作者
论文摘要
我们报告了波动旋转湍流的实验室实验。一组挥舞者会产生惯性波束，在安装在旋转平台上的水箱的中央区域中非线性相互作用。因此，强迫仅将能量注入惯性波。对于中等强迫幅度，通过标准的三合会共振不稳定性将强制惯性波的一部分转移到亚谐波波中。第一步大致符合弱湍流理论。然而，令人惊讶的是，强大的强迫不会导致惯性波湍流。取而代之的是，即使后者没有强制性，大多数动能都会凝结成垂直不变的地质流动。我们表明，惯性波的共鸣四重奏会触发不稳定性 - ``四障不稳定性'' - 导致这种自发的地球植物出现。在本实验中，这种不稳定性作为经典三合会不稳定性的二次不稳定性。
We report on laboratory experiments of wave-driven rotating turbulence. A set of wavemakers produces inertial-wave beams that interact nonlinearly in the central region of a water tank mounted on a rotating platform. The forcing thus injects energy into inertial waves only. For moderate forcing amplitude, part of the energy of the forced inertial waves is transferred to subharmonic waves, through a standard triadic resonance instability. This first step is broadly in line with the theory of weak turbulence. Surprisingly however, stronger forcing does not lead to an inertial-wave turbulence regime. Instead, most of the kinetic energy condenses into a vertically invariant geostrophic flow, even though the latter is unforced. We show that resonant quartets of inertial waves can trigger an instability -- the ``quartetic instability'' -- that leads to such spontaneous emergence of geostrophy. In the present experiment, this instability sets in as a secondary instability of the classical triadic instability.
