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

A. V. Kolesnichenko


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..

Keywords: turbulent astrophysical disc, compressibility effects, magnetic, transverse and residual helicity, dynamo theory.

DOI: 10.20948/prepr-2024-41