Meridional circulation in the Sun and stars

摘要: Mean-field hydrodynamics advanced to clear explanations for the origin and properties of global meridional flow in stellar convection zones. Qualitative arguments analysis basic equations both show that circulation is driven by non-conservative centrifugal buoyancy forces results from a slight disbalance between these two drivers. The deviations thermal wind balance are relatively large near boundaries Accordingly, attains its largest velocities boundary layers decreases inside zone. This picture, however, neither supported nor dismissed conflicting recent helioseismic soundings or 3D numerical experiments. relevant physics differential temperature possible relation solar oblateness briefly discussed.