The turbulence in free shear flows and in accretion discs

Abstract

Physical models of the development of turbulence in free shear flows and in accretion discs are proposed. The models are based on the results of numerical simulations of turbulent flow development. The main idea of the proposed theory of turbulence in free shear flow is stated as follows: the onset of turbulence begins with the formation of large vortices. The formation and evolution of large-scale turbulence in accretion discs are considered. It is shown that the kinetic energy of vortices forming in a turbulent flow is a virtually constant fraction of the initial kinetic energy of the rotating matter of an accretion disc. A possible mechanism explaining the transfer of angular momentum by large vortices that form in the disc without any noticeable heating of the matter is suggested.