Heat convection from a sphere placed in an oscillating free stream

The problem of heat convection from a sphere placed in an oscillating viscous free stream is considered for the two cases of forced and mixed convection regimes. The sphere surface is assumed isothermal and the free-stream oscillations are always in the vertical direction resulting in axisymmetric flow and thermal fields for both regimes. The study is based on the solution of the unsteady Navier-Stokes and energy equations for a Boussinesq fluid of constant Prandtl number (Pr=0.71). The main parameters considered are the Reynolds number, Grashof number, and Strouhal number. Comparison of results with published data shows a good agreement for the special case of steady forced and mixed convection. The details of the resulting thermal fields are presented in the form of isotherm patterns and the local Nusselt number distribution.