论文标题
速love被重新审视
The tachocline revisited
论文作者
论文摘要
太阳速率线是位于太阳对流区底部的剪切层。速裂中的水平剪切可能是湍流的，通常假定由于局部分层而导致这种湍流强烈各向异性。然而，这种湍流在速度线动力学中的作用尚待确定。特别是，尚不清楚这是否会导致湍流的涡流扩散，抗扩散性或其他东西。在本文中，我们介绍了在低prandtl数字下的水平剪切流中湍流的第一个直接数值模拟，这是一个理想化的模型，该模型忽略了旋转和磁场。我们发现存在几种方案，具体取决于分层，粘度和热扩散率的相对重要性。我们的结果表明，转速素处于分层的湍流状态，该湍流状态具有非常特异性的特性，该特性受浮力，惯性和热扩散之间的平衡。
The solar tachocline is a shear layer located at the base of the solar convection zone. The horizontal shear in the tachocline is likely turbulent, and it is often assumed that this turbulence would be strongly anisotropic as a result of the local stratification. What role this turbulence plays in the tachocline dynamics, however, remains to be determined. In particular, it is not clear whether it would result in a turbulent eddy diffusivity, or anti-diffusivity, or something else entirely. In this paper, we present the first direct numerical simulations of turbulence in horizontal shear flows at low Prandtl number, in an idealized model that ignores rotation and magnetic fields. We find that several regimes exist, depending on the relative importance of the stratification, viscosity and thermal diffusivity. Our results suggest that the tachocline is in the stratified turbulence regime, which has very specific properties controlled by a balance between buoyancy, inertia, and thermal diffusion.
