The interactions of the elliptical instability and convection
The interactions of the elliptical instability and convection
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DOI：
10.1063/5.0135932
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发表时间：
2023-02
影响因子：
4.6
通讯作者：
N. D. Vries;A. Barker;Rainer Hollerbach
中科院分区：
文献类型：
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作者：
N. D. Vries;A. Barker;Rainer Hollerbach
椭圆不稳定性是一种椭圆流线的不稳定性，它可以被旋转流体中的大尺度潮汐流激发，如果无量纲潮汐振幅（ε）足够大，则会激发惯性波。它在对流区工作，但它与湍流对流的相互作用尚未在这方面进行研究。我们在宽箱中进行了一系列广泛的笛卡尔流体动力学模拟，以探索椭圆不稳定性和瑞利-贝纳德对流的相互作用。我们发现，由椭圆形不稳定性产生的地转涡旋占主导地位的流动，与能量远远超过惯性波。此外，我们发现，椭圆形不稳定性可以与对流，但它是抑制足够强的对流，主要是由对流驱动的大尺度涡。我们研究流在傅立叶空间，使我们能够确定积极的主导频率和波数。我们发现，权力主要集中在地转涡，在对流不稳定的波数，和沿着惯性波色散关系，即使在非椭圆变形对流。检查线性增长率的对流背景下，我们发现，对流大尺度涡抑制椭圆形不稳定以同样的方式创建的椭圆形不稳定本身的地转涡。最后，对流运动作为大尺度潮汐流的有效粘性，提供持续的能量传递（缩放为ε2）。此外，我们发现，能量转移所造成的爆发椭圆不稳定性，当它的操作，是一致的ε3标度在以前的工作。
The elliptical instability is an instability of elliptical streamlines, which can be excited by large-scale tidal flows in rotating fluid bodies, and excites inertial waves if the dimensionless tidal amplitude (ε) is sufficiently large. It operates in convection zones but its interactions with turbulent convection has not been studied in this context. We perform an extensive suite of Cartesian hydrodynamical simulations in wide boxes to explore the interactions of the elliptical instability and Rayleigh-Bénard convection. We find that geostrophic vortices generated by the elliptical instability dominate the flow, with energies far exceeding those of the inertial waves. Furthermore, we find that the elliptical instability can operate with convection, but it is suppressed for sufficiently strong convection, primarily by convectively-driven large-scale vortices. We examine the flow in Fourier space, allowing us to determine the energetically dominant frequencies and wave numbers. We find that power primarily concentrates in geostrophic vortices, in wave numbers that are convectively unstable, and along the inertial wave dispersion relation, even in non-elliptically deformed convective flows. Examining linear growth rates on a convective background, we find that convective large-scale vortices suppress the elliptical instability in the same way as the geostrophic vortices created by the elliptical instability itself. Finally, convective motions act as an effective viscosity on large-scale tidal flows, providing a sustained energy transfer (scaling as ε2). Furthermore, we find that the energy transfer resulting from bursts of elliptical instability, when it operates, is consistent with the ε3 scaling found in prior work.