International Journal of Heat and Mass Transfer, Vol.41, No.24, 4121-4138, 1998
Multiple and unsteady solutions for buoyancy driven flows in spherical annuli
Results from the analysis of buoyancy driven flows and heat transfer in concentric spherical annuli heated by the inner surface are presented. Crescent eddy flows obtained at low Grashof numbers, Gr, are consistent with published results. Multicellular flows, ranging from steady bicellular to oscillating five-cell flows, are calculated for Gr(c) < Gr < Gr(r), the specific nature of the flows depending on gamma and Gr. For Gr > Gr(r), the solution reverts to Steady unicellular flows for the radial aspect ratios gamma = 0.2 and 0.25, but with hysteresis for gamma = 0.25. Heat transfer results, given in terms of the local and global Nusselt numbers, illustrate the effect of the flow structures on the heat transfer.