Heat transfer in a slip-flow past a sphere

Convective heat transfer from a sphere in a streaming flow of a viscous incompressible fluid is studied under mixed slip-slick boundary conditions. Using the method of matched asymptotic expansions, analytical expression for the mean Nusselt number Nu is obtained up to O(sigma(2)Re(2)), where Re < 1 is the Reynolds number based on uniform streaming and sigma of O(1) is the Prandtl number. The results show that for a given Re, heat transfer decreases with increasing slip. When a meridional spin is given to the body, it further decreases the heat transfer, though, quantitatively it is very marginal. This feature is in sharp contrast to the increased heat transfer due to rotation, observed in the absence of slip. (C) 1998 The Japan Society of Fluid Mechanics Incorporated and Elsevier Science B.V. All rights reserved.