The Evolving Phenomenological View on Magnetohydrodynamic Turbulence

Abstract

The current level of phenomenological MHD turbulence modelling is outlined together with recent results of experimental measurements and direct numerical simulations. After reviewing the spatially isotropic Kolmogorov and Iroshnikov-Kraichnan phenomenologies, the model of Goldreich and Sridhar is discussed, which introduces the concept of local anisotropy caused by the magnetic field. The She-L\'{ }vˆque picture of intermittency dealing with the anomalous scaling of the two-point e e structure functions is also considered, followed by a summary of the phenomenological theory of turbulent energy-decay. It is shown how the combination of phenomenology and numerical simulation leads to the physical model of homogeneous MHD turbulence.