Double-Cell Type Solar Meridional Circulation Based on Mean-Field   Hydrodynamic Model
  The main object of the paper is to present the condition of the non-diffusive part of the Reynolds stress for driving the double-cell structure of the solar meridional circulation, which has been revealed by recent helioseismic observations. By conducting a set of mean-field hydrodynamic simulations, we confirm for the first time that the double-cell meridional circulation can be achieved along with the solar-like differential rotation when the Reynolds stress transports the angular momentum upward in the lower part and downward in the upper part of the convection zone. It is concluded that, in a stationary state, the accumulated angular momentum via the Reynolds stress in the middle layer is advected to both the upper and lower parts of the convection zone by each of the two meridional circulation cells, respectively. 
Yuto Bekki, Takaaki Yokoyama
astro-ph.SR