| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程技術研究所 === 86 ===
A numerical calculation has been performed for the simultaneously develoing laminar velocity and temperature fields in the entrance fregion of rectaaangular uct which has isothermal walls of heated from below. The present thesis particularly addresses the effect of the aspect ratio of the rectangu8lar duct.
Unlike most of other methods, the present procedure solves all momenjtumk equations and takes full account of the pressu8re variation demonstrate thuat, when the boundary conditons exh ibit certain discontinuities, satisfactory results can only be obtained by solving all three momentum equations.
Results are presented for Prandtl number of 0.71; Reynolds numbers of 200,400 and 600; and cross-sectional aspect ratio of 1,2, and 5. It is fo und that flow an hueat transfer are strongly affected by an interaction between the boundary layer on the free stream and a recirculatttion zone. Hydrodynamic and thermal entrance lengths are drastically reduced with increasing Reynolds number.
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