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Paper: Turbulence in stellar interiors
Volume: 40, Inside the Stars, IAU Colloquium 137
Page: 236
Authors: Zahn, Jean-Paul
Abstract: The most recent work performed concerning turbulence in stellar interiors is reviewed. The latest numerical simulations, by Stein and Nordlund (1989) and Cataneo et al. (1991) show that turbulent convection is highly intermittent, with strong downdrafts carrying most of the energy flux. These plumes penetrate in the stable region below, which they render nearly adiabatic over some distance. They are also likely to exist in a convective core, and to penetrate into the radiative region above. Assuming that anisotropic turbulence ensures throughout the radiation zone a rotation state in which the angular velocity depends mainly on depth, it is possible to derive an explicit expression for the meridian flow, and thus to describe the evolution in time of the interior rotation. Both the meridian circulation and the turbulence are determined by the rate at which the star loses angular momentum. When there is no such loss, the meridian flow is very weak, and it can even vanish in slow rotators.
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