AAS 196th Meeting, June 2000 Session 26. The Galactic ISM:
Observations and Modelling  [Previous] | [Session 26] | [Next]
[26.02] The Effects of External Magnetic Fields on MHD
Turbulence  J. Cho (UTexas/JHU), E.T. Vishniac (JHU)  We have
studied the effects of uniform external magnetic fields on
driven magnetohydrodynamic (MHD) turbulence, including, as a
limit, the case of zero external field. We have two main
results. First, as the strength of the external field is
increased, the kinetic energy density drops by roughly the
product of the rms velocity (V) and the strength of the external
field (B0). The magnetic energy density rises by roughly the
same amount. Consequently, the rms magnetic field is always much
greater than the external field. Second, when the external
magnetic field (in velocity unit) is not very strong (say, less
than 0.1 times the rms velocity) the induced magnetic field
remains almost isotropic, i.e. there is no apparent anisotropy
of order B0/V. We discuss implications of these result