THE DEVELOPING NUSSELT NUMBERS FOR SLUG FLOW IN RECTANGULAR DUCTS

A rigorous solution is obtained for the 3-D temperature held in the th ermal entrance region of rectangular ducts, for Newtonian fluids in sl ug flow, with constant wall heat flux and fluid longitudinal heat Au,: (H2 boundary conditions). The solution is presented as a series of th e transverse Cartesian co-ordinates, where the coefficients depend on both the longitudinal co-ordinate and the different combinations of he ated and adiabatic walls. The thermal entrance lengths and the Nusselt numbers are calculated as functions of both the Graetz number and the aspect ratio. The temperature profiles, the thermal entrance lengths, and the Nusselt numbers are presented and discussed in tables and gra phs. (C) 1998 Elsevier Science Ltd. All rights reserved.