Universal Nonlinear Small-Scale Dynamo

Universal nonlinear small-scale dynamo.

We consider astrophysically relevant nonlinear MHD dynamo at large Reynolds numbers (Re). We argue that it is universal in a sense that magnetic energy grows at a rate which is a constant fraction C(E) of the total turbulent dissipation rate. On the basis of locality bounds we claim that this "efficiency of the small-scale dynamo", C(E), is a true constant for large Re and is determined only by...

Small-Scale-Field Dynamo.

Small-Scale Turbulent Dynamo

Kinematic dynamo theory is presented here for turbulent conductive fluids. We describe how inhomogeneous magnetic fluctuations are generated below the viscous scale of turbulence where the spatial smoothness of the velocity permits a systematic analysis of the Lagrangian path dynamics. We find analytically the moments and multipoint correlation functions of the magnetic field at small yet finit...

The Nonlinear Small-scale Dynamo and Isotropic Mhd Turbulence

Homogeneous incompressible MHD turbulence has been studied in the literature in two main regimes: with and without an externally imposed uniform mean magnetic field. In the former, explicitly anisotropic, case, Kolmogorov-style phenomenologies [3, 2] predict a state of detailed scale-by-scale equipartion between hydrodynamic and magnetic fluctuations, which are Alfvén waves propagating along th...

Small - scale turbulent dynamo - a numerical investigation

We present the results of a numerical investigation of the turbulent kinematic dynamo problem in a high Prandtl number regime. The scales of the magnetic turbulence we consider are far smaller than the Kolmogorov dissipative scale, so that the magnetic wavepackets evolve in a nearly smooth velocity field. Firstly, we consider the Kraichnan-Kazantsev model (KKM) in which the strain matrix is tak...