Quasi-two-dimensional MHD turbulence in three-dimensional flows

We simulate how nearly two-dimensional magnetohydrodynamic turbulence can b e initiated and how it evolves with distance in the third dimension. Expand ing flows lead to a suppression of the nonlinear cascades, mainly due to th e changing transverse length scales. Velocity fluctuation levels are determ ined more from the 2D dynamics than from the expansion except when the velo city fluctuations are initially dominant. With expansion, magnetic fluctuat ions always dominate velocity fluctuations at late times. [S0031-9007(98)08 244-1].