Thermal effects on axisymmetric vortex breakdown in a spherical gap

The thermal effects on vortex breakdown in a Boussinesq fluid contained within a rotating concentric spherical annulus are examined numerically for the case in which the outer sphere is stationary and hot while the inner sphere rotates and is at a lower temperature. An axial gravitational field is assumed. The investigation was done by means of a steady‐state axisymmetric finite‐element code. The method of solution was verified by analyzing the axisymmetric vortex breakdown with and without thermal effects in a closed circular‐cylindrical container with a rotating lid. Comparisons of the flow patterns with numerical results in the literature show good agreement. Solutions have been obtained for a spherical gap of radii ratio 0.5, Reynolds number 0≤Re≤6000, and Rayleigh number 0≤Ra≤1.5×106, at Prandtl number Pr=0.7. The results show that depending on the relative strength of the imposed temperature difference and rate of rotation, the flow field may be a large meridional circulation (‘‘base flow’’) with a ...