The effect of viscosity and resistivity on Rayleigh–Taylor instability induced mixing in magnetized high-energy-density plasmas
The effect of viscosity and resistivity on Rayleigh–Taylor instability induced mixing in magnetized high-energy-density plasmas
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DOI：
10.1017/s0022377821001343
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发表时间：
2021-06
影响因子：
2.5
通讯作者：
R. K. Bera;Yang Song;B. Srinivasan
中科院分区：
文献类型：
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作者：
R. K. Bera;Yang Song;B. Srinivasan
本文通过对等离子体和磁普朗特数的测量，数值研究了高阿特伍德数和高等离子体β的磁化高能量密度（HED）等离子体中粘度和电阻率在瑞利-泰勒不稳定性中的作用。采用粘阻磁流体动力学方程进行了数值模拟。结果表明，自一致粘度和电阻率的加入极大地改变了瑞利-泰勒不稳定性（RTI）的生长，并在较小尺度上改变了其内部结构。从这里可以看出，粘度对RTI具有稳定作用。此外，粘度抑制了小尺度结构的发展，也改变了RTI尖峰尖端的形态。另一方面，电阻率降低了磁场稳定性，支持了小规模结构的发展。RTI尖峰的形态不受系统中电阻率存在的影响。这项工作的另一个新颖之处在于，HED等离子体中可能存在不同的粘度和电阻率分布，以及它们对RTI生长、形态和由此产生的湍流光谱的影响。此外，本工作还表明，磁场的动力学与粘度无关，同样电阻率也不影响熵和动能的耗散。此外，在注入范围和惯性子范围内提供了熵、动能和磁场能量的幂律标度，这有助于理解HED实验室和天体物理等离子体中RTI诱导湍流混合，并有助于解释RTI诱导湍流光谱的观测结果。
This work numerically investigates the role of viscosity and resistivity in Rayleigh–Taylor instabilities in magnetized high-energy-density (HED) plasmas for a high Atwood number and high plasma beta regimes surveying across plasma beta and magnetic Prandtl numbers. The numerical simulations are performed using the visco-resistive magnetohydrodynamic equations. Results presented here show that the inclusion of self-consistent viscosity and resistivity in the system drastically changes the growth of the Rayleigh–Taylor instability (RTI) as well as modifies its internal structure at smaller scales. It is seen here that the viscosity has a stabilizing effect on the RTI. Moreover, the viscosity inhibits the development of small-scale structures and also modifies the morphology of the tip of the RTI spikes. On the other hand, the resistivity reduces the magnetic field stabilization, supporting the development of small-scale structures. The morphology of the RTI spikes is seen to be unaffected by the presence of resistivity in the system. An additional novelty of this work is in the disparate viscosity and resistivity profiles that may exist in HED plasmas and their impact on RTI growth, morphology and the resulting turbulence spectra. Furthermore, this work shows that the dynamics of the magnetic field is independent of viscosity and likewise the resistivity does not affect the dissipation of enstrophy and kinetic energy. In addition, power law scalings of enstrophy, kinetic energy and magnetic field energy are provided in both the injection range and inertial sub-range, which could be useful for understanding RTI induced turbulent mixing in HED laboratory and astrophysical plasmas and could aid in the interpretation of observations of RTI-induced turbulence spectra.