Friction and heat transfer in laminar free swirling flow in pipes

The apparent mean friction factor and the heat transfer coefficient for laminar free swirling flow in pipes have been calculated numerically for Re = 1000 and Pr = 0.7. The flow under consideration is axisymmetric and the governing equations including three momentum equations and one energy equation are elliptic. An existing numerical scheme is used to obtain the solution. The results indicate, for constant pumping power and fixed geometry, an increase in average Nusselt number over the fully-developed value without swirl by a factor of two at a location nine diameters from the inlet. This suggests that multiple swirl generators properly arranged in long pipes may be utilized to achieve heat transfer augmentation.