Influence of a density increase on the evolution of the Kelvin-Helmholtz instability and vortices

Тип публикации: статья из журнала

Год издания: 2010

Идентификатор DOI: 10.1063/1.3453705

Ключевые слова: A-density, Kelvin-Helmholtz instabilities, Linear growth, Loss rates, Nonlinear numerical simulation, Nonlinear phase, Nonregular structures, Plasma clouds, Plasma layer, Regular structure, Spatial scale, Turbulent phase, Upper layer, Boundary layers, Helmholtz equation, Ionosphere, Plasma density, Solar wind, Magnetoplasma

Аннотация: Results of two-dimensional nonlinear numerical simulations of the magnetohydrodynamic Kelvin-Helmholtz instability are presented. A boundary layer of a certain width is assumed, which separates the plasma in the upper layer from the plasma in the lower layer. A special focus is given on the influence of a density increase toward the lower layer. The evolution of the Kelvin-Helmholtz instability can be divided into three different phases, namely, a linear growth phase at the beginning, followed by a nonlinear phase with regular structures of the vortices, and finally, a turbulent phase with nonregular structures. The spatial scales of the vortices are about five times the initial width of the boundary layer. The considered configuration is similar to the situation around unmagnetized planets, where the solar wind (upper plasma layer) streams past the ionosphere (lower plasma layer), and thus the plasma density increases toward the planet. The evolving vortices might detach around the terminator of the planet and eventually so-called plasma clouds might be formed, through which ionospheric material can be lost. For the special case of a Venus-like planet, loss rates are estimated, which are of the order of estimated loss rates from observations at Venus. (C) 2010 American Institute of Physics. [doi:10.1063/1.3453705]

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Издание

Журнал: PHYSICS OF PLASMAS

Выпуск журнала: Vol. 17, Is. 7

ISSN журнала: 1070664X

Место издания: MELVILLE

Издатель: AMER INST PHYSICS

Авторы

  • Amerstorfer U.V. (Space Research Institute,Austrian Academy of Sciences)
  • Biernat H.K. (Institute of Physics,Karl-Franzens-University Graz)
  • Erkaev N.V. (Institute of Computational Modelling)
  • Taubenschuss U. (Department of Physics and Astronomy,University of Iowa)

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