Flow reversal in mixed convection in vertical concentric annuli

Esmail M.A. Mokheimer*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

Abstract

The main purpose of this article is to shed more light on the cause of flow reversal in vertical concentric annular channels for buoyancy-aided flows under isothermal boundary conditions. The concept used to quantify the critical values of the modified buoyancy parameter (Gr/Re)critical at which the adverse pressure gradient first occurs is outlined and applied to analytically estimate these critical values. The conditions for flow reversal are also analytically obtained for buoyancy aided and buoyancy-opposed flows. The analytical solutions show that pressure buildup takes place only for buoyancy-aided flows while flow reversal occurs for both buoyancy-aided and buoyancy-opposed flows. The analytical solutions reveal also that values of the buoyancy-parameter required to initiate the pressure buildup for buoyancy-aided flows in the vertical annuli are smaller than those required to initiate the flow reversal. Thus, for buoyancy aided flows, pressure buildup would precede the flow reversal. A numerical scheme is developed and used to simulate the development of pressure and pressure gradient in the entrance region of the vertical concentric annuli. The numerical scheme is validated by the analytical solution as well as the previously published pertinent results. Numerical results that show the pressure buildup in the developing entry region of the annuli for values of the modified buoyancy parameter (Gr/Re) greater than its critical values (Gr/Re)critical along with other flow and heat transfer parameters of importance are also presented and discussed. The locations of pressure build up as well as those of flow reversal have been obtained and reported. The numerical solutions show clearly that pressure buildup for buoyancy-aided flows takes place prior to the flow reversal onset.

Original languageEnglish
Title of host publicationProceedings of CHT-12. ICHMT International Symposium on Advances in Computational Heat Transfer, 2012
PublisherBegell House Inc.
Pages1155-1181
Number of pages27
ISBN (Print)9781567003031
DOIs
StatePublished - 2012

Publication series

NameInternational Symposium on Advances in Computational Heat Transfer
ISSN (Print)2578-5486

Bibliographical note

Publisher Copyright:
© 2012, Begell House Inc. All rights reserved.

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes
  • Mechanical Engineering
  • Condensed Matter Physics
  • Computer Science Applications

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