Influence of helicity and alpha effect on compressible hydromagnetic turbulence of astrophysical discs with strong magnetic field

Abstract

The influence of compressibility and rotation on turbulent transport in spiral hydromagnetic flows in the presence of an averaged velocity field and a global magnetic field is investigated using a phenomenological approach. The fluctuating effects, which are included in the averaged MHD equations through their correlation contributions and represent the Reynolds stress, turbulent electromotive force, and a number of other correlation functions, are modelled (at absence of reflection symmetry of small-scale plasma motions) using evolutionary equations and four spiral statistical characteristics of turbulence, which are: total turbulent plasma energy, dissipation rate, turbulent transverse helicity, turbulent residual energy and turbulent residual helicity. Four evolution equations for these bulk helicity quantities combined with the MHD mean-field equations leads, in particular, to a self-consistent dynamo model. The work is aimed at modelling the influence of compressibility effects on dynamical processes in hydromagnetic spiral turbulence of geo- and astrophysical objects of different nature..