Reynolds stresses and differential Rotation III. Zonal momentum fluxes in rapidly rotating stars

Abstract

Part II of this series of papers provided those modes of the Non-Diffusive Zonal momentum Fluxes (NDZF) which reproduce the observed profiles for the angular velocity and horizontal Reynolds stress of the Sun. In explaining the fluxes we now consider the influence of the Coriolis force on given turbulence models. For solar applications we find that the basic rotation must be assumed to be neither too slow nor too rapid in order to allow a non-trivial expansion of the NDZF. Two different turbulence fields provide the desired latitudinal profiles but give different radial rotation laws: turbulence with a dominant horizontal (vertical) intensity always yields equatorial acceleration as well as the observed horizontal Reynolds stresses in connection with radial superrotation, ∂Ω/∂r>0 (subrotation, ∂Ω/∂r<0). In both cases the turbulent cells must be rather flat.