Developing mixed convection in an inclined tube with circumferentially nonuniform heating at its outer surface

Conjugate heat transfer in an inclined tube combining developing mixed conv ection of a Boussinesq fluid with nonuniform heating of the outer tube surf ace has been studied numerically. Viscous dissipation and axial diffusion a re neglected. Thus the governing equations are parabolic in the axial direc tion and elliptic in the other two directions. Although the Bottom half of the outer tube surface is assumed adiabatic, circumferential conduction thr ough the wad results in a significantly different heat flux distribution at the solid-fluid interface. Thus, far from the entrance, the fraction of th e externally supplied heat reaching the fluid from the bottom half of the i nterface is 72% for copper, 60% for steel, and 30% for glass tubes. This si gnificant redistribution of the heat flux influences the thermal and hydrod ynamic fields and has important effects on the Nusselt number, which cannot be predicted if the thermal boundary condition is applied at the solid-flu id interface.