Toward a theory of spiral turbulence of a nonmagnetic astrophysical disk. Formation of large-scale vortex structures

Abstract

A closed system of three-dimensional hydrodynamic equations of the mean motion scale is presented for modeling spiral turbulence in a rotating astrophysical disk. The diffusion equations for the averaged vortex and the integral vortex spirality transport equation are derived. A general concept of the emergence of energy-consuming mezoscale coherent vortex structures in a thermodynamically open subsystem of turbulent chaos, associated with the realization of the inverse cascade of kine-tic energy in mirror-nonsymmetric disk turbulence, is formulated. It is shown that negative viscosity in the rotating disk three-dimensional system is apparently a manifestation of cascade processes in spiral turbulence, when an inverse energy transfer from small vortices to larger ones is realized. It is also shown that a relatively long decay of turbulence in the disk is associated with the absence of reflective symmetry of the anisotropic field of turbulent velocities relative to its equatorial plane. The work is of a review character, made with the aim of improving new models of astrophysical nonmagnetic disks for which the effects of spiral turbulence play a determining role.