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The rotational quenching of the rotation-induced kinetic alpha-effect
Authors:V V Pipin  G Rüdiger  L L Kitchatinov
Institution:1. Institute for Solar-Terrestrial Physics , P. O. Box 4026, Irkutsk, 664033, Russia;2. Astrophysikalisches Institut Potsdam , An der Sternwarte 16, D-14482, Potsdam, Germany;3. Astrophysikalisches Institut Potsdam , An der Sternwarte 16, D-14482, Potsdam, Germany;4. Institute for Solar-Terrestrial Physics , P. O. Box 4026, Irkutsk, 664033, Russia
Abstract:Abstract

A theory of the non-diffusive anisotropic kinetic alpha-effect (“Γ-effect”) for densitystratified rotating turbulent fluids is developed. No limitations on the rotation rate are imposed and the fully nonlinear dependence of the Γ-effect on the angular velocity is studied. When the Coriolis number, ω? = 2τ ω, is small the dimensionless “dynamo number”, Cτ, characterising the power of the Γ-effect, grows with ω?. The dependence, however, reaches a maximum for ω? ~ 2. For still higher rotation rates CΛ decreases as 1/ω?. In opposition, the corresponding number, Cx, of the hydromagnetic α2 -dynamo problems remains finite for very large ω?. Hence, for fast rotation the hydrodynamic Γ-effect is small while the hydromagnetic α-effect remains large. In consequence, the large-scale magnetic and velocity structures are expected to be generated with roughly equal power in slowly rotating objects. In the rapid rotators, however, generation of the large-scale flows is problematic.
Keywords:Turbulence  global rotation  stratification  large-scale vortices  galaxies  accretion disks
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