L. L. Kitchatinov, A. Brandenburg
Small levels of turbulence can be present in stellar radiative interiors due
to, e.g., instability of rotational shear. In this paper we estimate turbulent
transport coefficients for stably stratified rotating stellar radiation zones.
Stable stratification induces strong anisotropy with a very small ratio of
radial-to-horizontal turbulence intensities. Angular momentum is transported
mainly due to the correlation between azimuthal and radial turbulent motions
induced by the Coriolis force. This non-diffusive transport known as the
Lambda-effect has outward direction in radius and is much more efficient
compared to the effect of radial eddy viscosity. Chemical species are
transported by small radial diffusion only. This result is confirmed using
direct numerical simulations combined with the test-scalar method. As a
consequence of the non-diffusive transport of angular momentum, the estimated
characteristic time of rotational coupling (< 100 Myr) between radiative core
and convective envelope in young solar-type stars is much shorter compared to
the time-scale of Lithium depletion (~1 Gyr).
View original:
http://arxiv.org/abs/1201.2484
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