Anomalous transport by magnetohydrodynamic Kelvin-Helmholtz instabilities in the solar wind-magnetosphere interaction

Journal Article · Wed Feb 01 00:00:00 EST 1984 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA089iA02p00801· OSTI ID:7101928

Miura, A

A magnetohydrodynamic simulation of Kelvin-Helmholtz instabilities in a compressible plasma has been performed for parallel (v/sub 0/parallelB/sub 0/) and (v/sub 0/perpendicularB/sub 0/) configurations, modeling high-latitude (or downstream flanks) and dayside low-latitude magnetospheric boundaries. In the parallel configuration, a super-Alfvenic and transsonic shear flow (with 2<4 and M/sub s/ = V/sub 0//c/sub s/ = 1, where V/sub 0/ is the total jump of the velocity across the velocity shear layer) leads to an oscillation of the velocity shear layer, which bends the initial uniform magnetic field. With a hyper-Alfvenic shear flow (M/sub A/>4), the instability develops into a more turbulent state and the initial parallel shear flow develops into small eddies, which strongly twist, compress, and hence amplify the magnetic field by a dynamo action with an amplification factor M/sub A//2. In the nonlinear stage, however large the initial Alfven Mach number M/sub A/ may be, the magnetic field, amplified and twisted by the hydromagnetic flow vortices, eventually reacts back upon the flow evolution, and the flow vortices into smaller scale structures. In the transverse configuraion, for a fast magnetosonic Mach number M/sub f/( = V/sub 0//(c/sub s//sup 2/+v/sub A//sup 2/)/sup 1/2/) greater than a critical Mach number, the instability leads to the formation of a fast shock discontinuity from an initially subfast shear flow.

• Research Organization: Institute of Geophysics and Planetary Physics, University of California, Los Angeles
• OSTI ID: 7101928
• Journal Information: J. Geophys. Res.; (United States), Vol. 89:A2
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPRESSIBLE FLOW
HELMHOLTZ INSTABILITY
MAGNETOSPHERE
SOLAR WIND
DIFFUSION
MACH NUMBER
MAGNETOHYDRODYNAMICS
PLASMA SIMULATION
SHEAR
TURBULENCE
VISCOUS FLOW
VORTEX FLOW
EARTH ATMOSPHERE
FLUID FLOW
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
MECHANICS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
SIMULATION
SOLAR ACTIVITY
VELOCITY
640203* - Atmospheric Physics- Magnetospheric Phenomena- (-1987)