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arXiv 1604.01546astro-ph.SR
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Kelvin-Helmholtz不稳定性的数值模拟:二维参数研究

Numerical simulations of Kelvin-Helmholtz instability: a two-dimensional parametric study

Chunlin Tian, Yao Chen

摘要:

使用二维模拟,我们数值研究了Kelvin-Helmholtz不稳定性对各种物理参数的依赖性,包括粘度,剪切层宽度,流速和磁场强度。在大多数情况下,多涡阶段存在于初始增长阶段和最终的单涡阶段之间。参数研究表明,演变的性质,如相持续时间和涡动力学,一般敏感的这些参数,除了在某些制度。一个有趣的结果是,对于超声速流动,相持续时间和饱和速度增长渐近地接近恒定值,随着音速马赫数的增加。我们证实,如果磁场足够弱,则磁场与Kelvin-Helmholtz模之间的线性耦合可以忽略。形态学的行为表明,多涡合并可能是由底层的波-波相互作用。在此基础上,我们对日冕中观测到的几个事件作了初步的讨论。数值模型需要进一步改进,使日冕等离子体的属性的实际诊断。

英文摘要:

Using two-dimensional simulations, we numerically explore the dependences of Kelvin-Helmholtz instability upon various physical parameters, including viscosity, width of sheared layer, flow speed, and magnetic field strength. In most cases, a multi-vortex phase exists between the initial growth phase and final single-vortex phase. The parametric study shows that the evolutionary properties, such as phase duration and vortex dynamics, are generally sensitive to these parameters except in certain regimes. An interesting result is that for supersonic flows, the phase durations and saturation of velocity growth approach constant values asymptotically as the sonic Mach number increases. We confirm that the linear coupling between magnetic field and Kelvin-Helmholtz modes is negligible if the magnetic field is weak enough. The morphological behaviour suggests that the multi-vortex coalescence might be driven by the underlying wave-wave interaction. Based on these results, we make a preliminary discussion about several events observed in the solar corona. The numerical models need to be further improved to make a practical diagnostic of the coronal plasma properties.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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