TRANSPORT PHENOMENA OF DEVELOPING LAMINAR MIXED CONVECTION HEAT AND MASS-TRANSFER IN INCLINED RECTANGULAR DUCTS

The developing laminar mixed convection heat and mass transfer in incl ined rectangular ducts has been studied numerically, with six independ ent parameters: Prandtl number Pr, mixed convection parameter Omega, m odified Rayleigh number Ra, buoyancy ratio N, Schmidt number Sc and a spect ratio gamma. Typical developments of velocity, temperature and c oncentration profiles are shown to include the limiting cases of horiz ontal and vertical rectangular duels. Local friction factor, Nusselt n umber and Sherwood number are presented for species diffusion of inter est in air (Pr = 0.7) over a Schmidt number range of 0.2-2.0. The resu lts show that the Nu(Sh) is characterized by a decay near the inlet du e to the entrance effect; but the decay is attenuated by the onset of buoyancy-driven secondary flows. The Nu (Sh) falls asymptotically to t he value of Graetz problem when the temperature (concentration) profil e becomes fully developed. The fRe/(fRe)(0), Nu and Sh are enhanced as the buoyancy force from species diffusion assists the thermal buoyanc y force.