标题： 向一个自洽的日冕流体动力学模型迈进 显示英文标题

标题： Towards a self-consistent hydrodynamical model of the solar tachocline

摘要： 太阳耀斑边界层是太阳内部的一个内边界层，位于不同的旋转对流区和下面均匀旋转的辐射区内。 斯派格尔和扎恩（1992年）提出了第一个流体力学模型，我们在这里称之为SZ92，认为耀斑边界层本质上处于热风平衡、角动量平衡和热平衡的稳态。 在他们的模型中，角动量传输被认为主要由强烈的各向异性湍流主导，由于辐射区的强烈稳定分层，这种湍流主要是水平方向的。 相比之下，热量传输则被认为是由于耀斑边界层的薄度而主要由垂直扩散的热通量主导。 在本文中，我们证明了这些假设与奇尼等人（2022年）和沙阿等人（2024年）最近提出的分层湍流新模型不一致，该模型已被加拉乌德等人（2024年）通过数值验证。 然后，我们提出了一种简单的自洽替代方案来代替SZ92模型，即一种情景，在其中角动量和热量传输都由水平湍流扩散主导。 新模型中的耀斑边界层厚度按 $\Omega_\odot / N_m$ 的比例变化，其中 $\Omega_\odot$ 是太阳的平均角速度，$N_m$ 是耀斑区域内的浮力频率。 我们讨论了模型的其他特性，并表明它具有几个理想的特性，但并未解决SZ92模型的其他一些众所周知的问题。 显示英文摘要

摘要： The solar tachocline is an internal boundary layer in the Sun located between the differentially-rotating convection zone and the uniformly-rotating radiative interior beneath. Spiegel and Zahn (1992) proposed the first hydrodynamical model, which here we call SZ92, arguing that the tachocline is essentially in a steady state of thermal-wind balance, angular-momentum balance, and thermal equilibrium. Angular momentum transport in their model is assumed to be dominated by strongly anisotropic turbulence, primarily horizontal owing to the strong stable stratification of the radiative interior. By contrast, the heat transport is assumed to be dominated by a predominantly vertical diffusive heat flux owing to the thinness of the tachocline. In this paper, we demonstrate that these assumptions are not consistent with the new model of stratified turbulence recently proposed by Chini et al. (2022) and Shah et al. (2024), which has been numerically validated by Garaud et al. (2024). We then propose a simple self-consistent alternative to the SZ92 model, namely, a scenario wherein angular momentum and heat transport are both dominated by horizontal turbulent diffusion. The thickness of the tachocline in the new model scales as $\Omega_\odot / N_m$, where $\Omega_\odot$ is the mean angular velocity of the Sun, and $N_m$ the buoyancy frequency in the tachocline region. We discuss other properties of the model, and show that it has several desirable features, but does not resolve some of the other well-known problems of the SZ92 model.