Buoyancy-assisted flow reversal and convective heat transfer in entrance region of a vertical rectangular duct

In this study, predictions of buoyancy-assisted flow reversal and convectiv e heat transfer in the entrance region of a vertical rectangular duct are r eported for the first time. In line with the current trend toward the use o f computationally efficient numerical methods. the present study is based o n the use of a three-dimensional parabolic, boundary-layer model and the FL ARE approximation. Physical situations investigated include cases with vari ous asymmetric heating conditions over wide ranges of parameters. Analytica l solutions for the fully developed flows are also presented, and the crite ria for the flow reversal to occur are predicted. Solutions for the develop ing flow obtained in this study agree closely with the elliptic-model solut ions, and precisely approach the fully developed solutions downstream. (C) 2000 Elsevier Science Inc. All rights reserved.