Meridional circulation in young massive stars with laminar rotation

We study the rotation of a chemically homogeneous star with a mass of 16M_⊙, assuming that the angular-momentum distribution in its radiative envelope is determined by hydrodynamical processes—flows and turbulent diffusion. Meridional circulation and horizontal shear turbulence are the main hydrodynamical processes forming the radial distribution of the angular momentum in young massive stars in the absence of magnetic fields. The rotation of such stars is close to steady-state. The angular velocity of rotation of the convective core can be ～5–20% higher than the surface value. Under these conditions, the characteristic time for the radial transport of angular momentum by meridional flows and shear turbulence is comparable to the nuclear time scale.