In this study, predictions of buoyancy-assisted flow reversal and convective heat transfer in the entrance region of a vertical rectangular duct are reported for the first time. In line with the current trend toward the use of computationally efficient numerical methods, the present study is based on the use of a three-dimensional parabolic, boundary-layer model and the FLARE approximation. Physical situations investigated include cases with various asymmetric heating conditions over wide ranges of parameters. Analytical solutions for the fully developed flows are also presented, and the criteria for the flow reversal to occur are predicted. Solutions for the developing flow obtained in this study agree closely with the elliptic-model solutions, and precisely approch the fully developed solutions downstream. (C) 2000 Elsevier Science Inc. All rights reserved.
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