Local skin friction and heat transfer in combined free-forced convection from a cylinder or sphere to a power-law fluid

Abstract

Steady-state laminar heat transfer mechanisms of polymeric liquids flowing across a horizontal cylinder or past a sphere of different wall temperatures have been analyzed. The uniquely transformed conservation equations of this nonsimilar problem have been solved with an implicit finite difference method up to the point of boundary layer separation. Of interest are the effects of the power-law index, the buoyancy parameter, and a generalized Prandtl number on the local skin friction coefficient and the local Nusselt number. Both the dimensionless skin friction group and the heat transfer group increase with higher buoyancy effects for any power-law fluid. Furthermore, increasing the buoyancy force will delay the point of flow separation. Dilatant fluids exhibit a distinctively different heat transfer behavior than pseudoplastics in the vicinity of the stagnation point. Higher Prandtl numbers generate lower skin friction and larger heat transfer coefficients.