Le Reun Thomas, Favier Benjamin, Barker Adrian J, Le Bars Michael
Aix Marseille Univ, CNRS, Centrale Marseille, IRPHE UMR 7342, Marseille, France.
Department of Applied Mathematics, School of Mathematics, University of Leeds, Leeds LS2 9JT, United Kingdom.
Phys Rev Lett. 2017 Jul 21;119(3):034502. doi: 10.1103/PhysRevLett.119.034502.
The combination of elliptical deformation of streamlines and vorticity can lead to the destabilization of any rotating flow via the elliptical instability. Such a mechanism has been invoked as a possible source of turbulence in planetary cores subject to tidal deformations. The saturation of the elliptical instability has been shown to generate turbulence composed of nonlinearly interacting waves and strong columnar vortices with varying respective amplitudes, depending on the control parameters and geometry. In this Letter, we present a suite of numerical simulations to investigate the saturation and the transition from vortex-dominated to wave-dominated regimes. This is achieved by simulating the growth and saturation of the elliptical instability in an idealized triply periodic domain, adding a frictional damping to the geostrophic component only, to mimic its interaction with boundaries. We reproduce several experimental observations within one idealized local model and complement them by reaching more extreme flow parameters. In particular, a wave-dominated regime that exhibits many signatures of inertial wave turbulence is characterized for the first time. This regime is expected in planetary interiors.
流线的椭圆变形与涡度的结合会通过椭圆不稳定性导致任何旋转流的失稳。这种机制被认为是受潮汐变形影响的行星内核中湍流的一个可能来源。椭圆不稳定性的饱和已被证明会产生由非线性相互作用的波和具有不同各自振幅的强柱状涡旋组成的湍流，这取决于控制参数和几何形状。在本快报中，我们进行了一系列数值模拟，以研究饱和以及从涡旋主导到波主导 regime 的转变。这是通过在一个理想化的三重周期域中模拟椭圆不稳定性的增长和饱和来实现的，仅对地转分量添加摩擦阻尼，以模拟其与边界的相互作用。我们在一个理想化的局部模型中重现了几个实验观测结果，并通过达到更极端的流动参数对其进行补充。特别是，首次表征了一个表现出许多惯性波湍流特征的波主导 regime。这种 regime 在行星内部是可以预期的。
