Results from numerical simulation of laminar forced convection flow adjacent to a 3-D backward-facing step in a duct is presentd for the case where the duct's aspect ratio is eight (AR chemical bounds 8), its expansion ratio is two (ER chemical bounds 2), and the step height (S) is 1.00 cm. The results illustrate the complex three-dimensional flow and heat transfer characteristics in the separated and developing flow region downstream from the step. The flow, upstream of the step, is treated as fully developed and isothermal. The duct walls are treatd as adiabatic surfaces with the exception of the lower wall that is downstream from the step which is treated as being heated with a constant and uniform heat flux. The relatively small aspect ratio of the duct is selected specifically to focus on the developments of the three-dimensional behavior. A vortex flow develops near the sidewall downstream from the step, and this three dimensional feature increases with increasing Rynolds number. This vortx is responsible for crating, in the spanwise distribution, a minimum in the reattachment length and a maximum in the Nusselt number near the sidewall. The distributions of the three-velocity components, temperature, reattachement lenght, friction coefficient, and Nusselt number are presented, discussed, and compared with 2-D results.
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