Effect of Temperature-Dependent Viscosity on Laminar Forced Convection in the Entrance Region of a Circular Pipe

Abstract

Predictions and measurements are reported of heat transfer to a viscous oil at uniform wall-heat flux in the entrance region of a pipe of circular cross-section. This work extends an earlier investigation of isothermal flow to simultaneous development of the hydrodynamic and thermal boundary layers where the extent of viscosity variation is influenced both by the applied heat flux and the viscous heat generation. The effect of the contribution of viscous heating to the delay in flow development at high Prandtl numbers is also discussed.