Effect of Reynolds Number on Inclined HeatedSemicircular Ducts at Different Rotations

Fully developed laminar mixed convection in inclined semicircular ducts is investigated numerically for the specific case of uniform heat input along the axial direction and uniform peripheral wall temperature, H1. The duct is considered over a variety of orientations (rotations) of its cross section, ranging from 0o (flat wall horizontally facing upward) to 180o (flat wall horizontally facing downward) with increment of 45o and a fixed inclination of its axis (with respect to the direction of gravity). In particular, the following conditions are considered: inclination α = 20o, 300 ≤ Re ≤ 1000, Pr = 4 and Gr = 1 x 107. The combined effects induced by changes in the Reynolds number and duct orientation are presented in terms of the isovelcity and isotherm contours for the 0o and 90o cases (the flat wall in a vertical position). A decrease in the Reynolds number is shown to increase the heat transfer rate for all cross section orientations considered (more significant for the 90o orientation). The results also reveal a reduction in the friction factor when the 90o orientation is considered.