THE INFLUENCE OF A MEAN MAGNETIC-FIELD ON 3-DIMENSIONAL MAGNETOHYDRODYNAMIC TURBULENCE

Building on results from two-dimensional magnetohydrodynamic (MHD) tur bulence (Shebalin, Matthaeus and Montgomery 1983), the development of anisotropic states from initially isotropic ones is investigated numer ically for fully three-dimensional incompressible MHD turbulence. It i s found that when an external d.c. magnetic field (B-0) is imposed on viscous and resistive MHD systems, excitations are preferentially tran sferred to modes with wavevectors perpendicular to B-0. The anisotropy increases with increasing mechanical and magnetic Reynolds numbers, a nd also with increasing wavenumber. The tendency of B-0 to inhibit dev elopment of turbulence is also examined.