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

Journal Article · Thu Jul 15 04:00:00 EDT 2010 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3453705· OSTI ID:21389127

Amerstorfer, U V ^[1]; Erkaev, N V ^[2]; Taubenschuss, U ^[3]; Biernat, H K ^[1]

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1. Space Research Institute, Austrian Academy of Sciences, 8042 Graz (Austria)
2. Siberian Federal University, 660041 Krasnoyarsk (Russian Federation)
3. Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242-1479 (United States)

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.

• OSTI ID: 21389127
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 7 Vol. 17; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ASTROPHYSICS
BOUNDARY LAYERS
COMPUTERIZED SIMULATION
HELMHOLTZ INSTABILITY
INSTABILITY
LAYERS
NONLINEAR PROBLEMS
PHYSICS
PLANETS
PLASMA
PLASMA DENSITY
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PLASMA SIMULATION
SIMULATION
SOLAR ACTIVITY
SOLAR WIND
STELLAR ACTIVITY
STELLAR WINDS
TWO-DIMENSIONAL CALCULATIONS
VENUS PLANET
VORTICES