SIMULATION STUDY OF THE MHD INSTABILITIES CAUSED BY THE SHEARED FLOW AT THE BOUNDARYLAYER OF THE MAGNETOSPHERE
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摘要: 本文用MHD二维不可压模式, 对Kelvin-Helmholtz不稳定性激发的非线性波动进行数值模拟.指出:K-H波动有两个吸引子:(1)定常吸引子;(2)周期吸引子.在Alfvén马赫数MA>8时, 波动长时间发展渐近于定常态;在MA<8时, 波动渐近于周期吸引子.在磁层顶K-H波动中, 一般MA<8, 波动幅度呈周期变化形态, 即包络孤立子形态.本文还讨论了磁场-磁层顶K-H不稳定性中的作用, 指出:磁场可大大加强从磁鞘向磁层顶的动量输运.Abstract: Atwo dimension incompressive MHDsimulation is carried out to study the nonlinear waves caused by Kelvin-Helmholtz instability. It is found that three are two attractors. When MA>8, the system develops towards a steady state one; When MA<8, it develops towards a periodic attractor. At the boundarylayer of the magnetosphere, the condition of MA<8 is sa-tified. As a result the amplitude of the K-Hwaves should change periodically. The role of magnetic field in K-Hinstability is also studied. The magnetic field may make the transport of the momentum more efficient.
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