The effects of non-linearities on tidal flows in the convective envelopes of rotating stars and planets in exoplanetary systems
The effects of non-linearities on tidal flows in the convective envelopes of rotating stars and planets in exoplanetary systems
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非线性对系外行星系统中旋转恒星和行星对流包层潮汐流的影响
DOI：
10.1093/mnras/stac2117
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发表时间：
2022
影响因子：
4.8
通讯作者：
Astoul A
中科院分区：
文献类型：
--
作者：
Astoul A
在紧密的系外行星系统中，潮汐相互作用驱动着行星和恒星在长时间尺度上的轨道和自转演化。低质量恒星和巨型气态行星对流包层中的潮汐强迫惯性波(由科里奥利加速度恢复)对潮汐耗散有很大贡献，当它们被激发并随后被抑制(例如，通过粘性摩擦)时，特别是在系统生命的早期。众所周知，这些波受到非线性效应的影响，包括以纬向流的形式触发差异旋转。在这项研究中，我们使用一个真实的潮汐物体，通过波浪动量方程中平衡潮汐的剩余作用来激发惯性波。通过在绝热和不可压缩对流壳体中进行三维非线性流体动力学模拟，研究了非线性项的加入对潮流性质以及能量和角动量重新分布的影响。具体地说，我们确定并证明了移除导致先前数值研究中观察到的非物理角动量演化的项的合理性。在我们的新装置中，我们观察到强圆柱切变纬向流的建立，它修正了先前线性理论预测的潮汐耗散率。我们证明，在我们的许多模拟中，这种差异旋转对波的影响很好地解释了线性和非线性耗散率之间的差异。我们还强调了惯性波的自转共振和参数不稳定性在影响潮流响应中的主要作用，这是在足够高的潮汐强迫幅度或低粘度时观察到的。
In close exoplanetary systems, tidal interactions drive orbital and spin evolution of planets and stars over long time-scales. Tidally forced inertial waves (restored by the Coriolis acceleration) in the convective envelopes of low-mass stars and giant gaseous planets contribute greatly to the tidal dissipation when they are excited and subsequently damped (e.g. through viscous friction), especially early in the life of a system. These waves are known to be subject to non-linear effects, including triggering differential rotation in the form of zonal flows. In this study, we use a realistic tidal body forcing to excite inertial waves through the residual action of the equilibrium tide in the momentum equation for the waves. By performing 3D non-linear hydrodynamical simulations in adiabatic and incompressible convective shells, we investigate how the addition of non-linear terms affects the tidal flow properties, and the energy and angular momentum redistribution. In particular, we identify and justify the removal of terms responsible for unphysical angular momentum evolution observed in a previous numerical study. Within our new set-up, we observe the establishment of strong cylindrically sheared zonal flows, which modify the tidal dissipation rates from prior linear theoretical predictions. We demonstrate that the effects of this differential rotation on the waves neatly explains the discrepancies between linear and non-linear dissipation rates in many of our simulations. We also highlight the major role of both corotation resonances and parametric instabilities of inertial waves, which are observed for sufficiently high tidal forcing amplitudes or low viscosities, in affecting the tidal flow response.