How tidal waves interact with convective vortices in rapidly rotating planets and stars
How tidal waves interact with convective vortices in rapidly rotating planets and stars
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潮汐波如何与快速旋转的行星和恒星中的对流涡旋相互作用
DOI：
10.1051/0004-6361/202243586
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发表时间：
2023
影响因子：
6.5
通讯作者：
Dandoy V
中科院分区：
文献类型：
--
作者：
Dandoy V
行星和恒星对流区潮汐惯性波的耗散是驱动恒星-行星和行星-月球系统演化的关键机制之一。这种耗散对于年轻的低质量恒星和气态巨行星特别有效，它们是快速旋转的。在这种情况下，潮汐惯性波和湍流对流之间的相互作用，必须以现实和强大的方式建模。在最先进的模拟中，对流对潮汐波施加的摩擦通常被建模为有效的涡动粘度。当对流涡旋的特征尺度小于潮波的特征尺度时，这种方法是有效的。然而，在潮汐波与潜在稳定的大规模涡旋（例如在木星和土星两极观察到的涡旋）相互作用的情况下，这就变得非常值得怀疑。大尺度涡是潜在的触发对流在快速旋转的机构，其中的科里奥利加速度形成流动的柱状涡结构沿着方向的旋转axis.AimsWe调查之间的复杂的相互作用的潮汐惯性波和柱状对流vortex.MethodsWe使用的准地转半解析模型的对流柱涡，这是通过数值模拟验证。首先，我们进行了线性稳定性分析，使用数值和渐近Wentzel-Kramers-Brillouin-Jeffreys（WKBJ）方法。然后我们进行了线性数值模拟的对流柱涡和传入的潮汐惯性wave.ResultsThe涡，我们认为是离心稳定的范围内-Ωp≤ Ω0≤ 3.62Ω p和不稳定的范围外，其中Ω 0是当地的旋转速度的涡在其中心和Ω p是全球行星（恒星）的旋转速度。从线性稳定性分析中，我们发现该涡旋在方位波数sm = {0，1，2}的扰动下容易发生离心不稳定，这可能分别对应于偏心率、偏心率和异步潮汐。当m> 2时，模是中性的或稳定的。当轴向（垂直）波数足够大时，WKBJ分析提供了中性和不稳定模式色散关系的解析表达式。我们验证，在不稳定的制度，传入的潮汐惯性波触发的最不稳定模式的旋涡的增长。这将导致湍流消散。对于稳定的对流柱，波涡相互作用导致的潮汐惯性波的动量的混合，而它创建一个低速区周围的涡核和一个新的波状扰动的形式的前进波辐射在远场。当入射波的波长接近涡旋的特征尺寸（半径）时，这种二次波的发射最强。传入的潮汐波也可以经历复杂的角动量交换本地在临界层的稳定vortices.ConclusionsThe潮汐惯性波和大规模的相干对流涡在快速旋转的行星（恒星）之间的相互作用导致湍流耗散的不稳定制度和复杂的行为，如混合的动量和辐射的新波在远场或波涡角动量交换稳定制度。这些现象不能用简单的有效涡动粘度来模拟。
ContextThe dissipation of tidal inertial waves in planetary and stellar convective regions is one of the key mechanisms that drive the evolution of star–planet and planet–moon systems. This dissipation is particularly efficient for young low-mass stars and gaseous giant planets, which are rapid rotators. In this context, the interaction between tidal inertial waves and turbulent convective flows must be modelled in a realistic and robust way. In the state-of-the-art simulations, the friction applied by convection on tidal waves is commonly modeled as an effective eddy viscosity. This approach may be valid when the characteristic length scales of convective eddies are smaller than those of the tidal waves. However, it becomes highly questionable in the case where tidal waves interact with potentially stable large-scale vortices such as those observed at the poles of Jupiter and Saturn. The large-scale vortices are potentially triggered by convection in rapidly-rotating bodies in which the Coriolis acceleration forms the flow in columnar vortical structures along the direction of the rotation axis.AimsWe investigate the complex interactions between a tidal inertial wave and a columnar convective vortex.MethodsWe used a quasi-geostrophic semi-analytical model of a convective columnar vortex, which is validated by numerical simulations. First, we carried out linear stability analysis using both numerical and asymptotic Wentzel–Kramers–Brillouin–Jeffreys (WKBJ) methods. We then conducted linear numerical simulations of the interactions between a convective columnar vortex and an incoming tidal inertial wave.ResultsThe vortex we consider is found to be centrifugally stable in the range –Ωp≤ Ω0≤ 3.62Ωpand unstable outside this range, where Ω0is the local rotation rate of the vortex at its center and Ωpis the global planetary (stellar) rotation rate. From the linear stability analysis, we find that this vortex is prone to centrifugal instability with perturbations with azimuthal wavenumbersm= {0,1, 2}, which potentially correspond to eccentricity, obliquity, and asynchronous tides, respectively. The modes withm> 2 are found to be neutral or stable. The WKBJ analysis provides analytic expressions of the dispersion relations for neutral and unstable modes when the axial (vertical) wavenumber is sufficiently large. We verify that in the unstable regime, an incoming tidal inertial wave triggers the growth of the most unstable mode of the vortex. This would lead to turbulent dissipation. For stable convective columns, the wave-vortex interaction leads to the mixing of momentum for tidal inertial waves while it creates a low-velocity region around the vortex core and a new wave-like perturbation in the form of a progressive wave radiating in the far field. The emission of this secondary wave is the strongest when the wavelength of the incoming wave is close to the characteristic size (radius) of the vortex. Incoming tidal waves can also experience complex angular momentum exchanges locally at critical layers of stable vortices.ConclusionsThe interaction between tidal inertial waves and large-scale coherent convective vortices in rapidly-rotating planets (stars) leads to turbulent dissipation in the unstable regime and complex behaviors such as mixing of momentum and radiation of new waves in the far field or wave-vortex angular momentum exchanges in the stable regime. These phenomena cannot be modeled using a simple effective eddy viscosity.
旋转、分层和导电流体中的湍流：湍流的基本性质
DOI：
--
发表时间：
2013
期刊：
影响因子：
--
作者：
P. A. Davidson
通讯作者：
P. A. Davidson
DOI：
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发表时间：
1999
期刊：
--
影响因子：
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作者：
R. Grimshaw
通讯作者：
R. Grimshaw