Eur. Phys. J. B 38, 117-126 (2004)
https://doi.org/10.1140/epjb/e2004-00107-0

Dynamo mechanism: Effects of correlations and viscosities

Abteilung Theorie, Hahn-Meitner-Institut, Glienicker Strasse 100, 14109 Berlin, Germany and Poornaprajna Institute of Scientific Research, Bangalore, India

Corresponding author: ^a abhik@physics.iisc.ernet.in

Received: 20 August 2003
Revised: 14 November 2003
Published online: 20 April 2004

Abstract

We analyze the effects of the background velocity and the initial magnetic field correlations, and viscosities on the turbulent dynamo and the α-effect. We calculate the α-coefficients for arbitrary magnetic and fluid viscosities, background velocity and the initial magnetic field correlations. We explicitly demonstrate that the general features of the initial growth and late-time saturation of the magnetic fields due to the non-linear feedback are qualitatively independent of these correlations. We also examine the hydrodynamic limit of the magnetic field growth in a renormalization group framework and discuss the possibilities of suppression of the dynamo growth below a critical rotation. We demonstrate that for Kolmogorov-(K41) type of spectra the Ekman number for dynamo growth to occur.