A&A 416, 825-827 (2004)
DOI: 10.1051/0004-6361:20034519

Research Note

A note on transition, turbulent length scales and transport in differentially rotating flows

D. Richard and S. S. Davis

NASA Ames Research Center, MS 245-3, Moffett Field, California 94035, USA
(Received 16 October 2003 / Accepted 8 January 2004)

Abstract
In this note we address the issue of hydrodynamical instabilities in Astrophysical rotating shear flows in the light of recent publications focused on the possibility for differential rotation to trigger and sustain turbulence in the absence of a magnetic field. We wish to present in a synthetic form the major arguments in favor of this thesis along with a simple schematic scenario of the transition to and self-sustenance of such turbulence. We also propose that the turbulent diffusion length scale scales as the local Rossby number of the mean flow. A new prescription for the turbulent viscosity is introduced. This viscosity reduces to the so-called -prescription in the case of velocity profiles with a constant Rossby number, which includes Keplerian rotating flows.

Key words: hydrodynamics -- instabilities -- turbulence

Offprint request: D. Richard, drichard@mail.arc.nasa.gov

© ESO 2004

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