NATURAL CONVECTION ABOUT A SPHERE AT LOW GRASHOF NUMBER
Laminar natural convection flow and heat transfer about an isothermal sphere is analysed for the Grashof number range between zero and unity and for Prandtl number around unity, by means of an asymptotic expansion technique. Solutions to the governing differential equations
are expressed in a series with the Grashof number taken as the expansion parameter. Three terms in the expansion for the temperature and for the stream function have been determined analytically and the results are presented and discussed. Unexpected vortex regions, are found. The reasons for difficulties in applying direct perturbation
and matched expansions are also, in short, discussed.