完全可压缩多方大气中的切变不稳定性
Shear instabilities in a fully compressible polytropic atmosphere
摘要：
剪切流对各种不同的天体物理学对象，包括认证盘和恒星内部的动力学有重要的影响。在多方大气中研究剪切流不稳定性提供了对恒星内部运动的基本理解，在那里湍流运动，混合过程，以及磁场的产生发生。在这里，一个完全可压缩的流体在二维笛卡尔几何的线性稳定性分析进行。我们的研究重点是确定不同马赫数的临界Richardson数和高热扩散的失稳效应。我们发现，对于中等马赫数流动，预测的稳定性阈值存在偏差，同时对于小Péclet数，线性不稳定性的增长率也有显著影响。我们发现，除了开尔文-亥姆霍兹不稳定性的Holmboe不稳定性可以出现，我们讨论了这在恒星内部的含义。
英文摘要：
Shear flows have an important impact on the dynamics in an assortment of different astrophysical objects including accreditation discs and stellar interiors. Investigating shear flow instabilities in a polytropic atmosphere provides a fundamental understanding of the motion in stellar interiors where turbulent motions, mixing processes, as well as magnetic field generation takes place. Here, a linear stability analysis for a fully compressible fluid in a two-dimensional Cartesian geometry is carried out. Our study focuses on determining the critical Richardson number for different Mach numbers and the destabilising effects of high thermal diffusion. We find that there is a deviation of the predicted stability threshold for moderate Mach number flows along with a significant effect on the growth rate of the linear instability for small Péclet numbers. We show that in addition to a Kelvin-Helmholtz instability a Holmboe instability can appear and we discuss the implication of this in stellar interiors.
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