Turbulence characteristics and vortical structures in combined-convection boundary layers along a heated vertical flat plate

Mohammad Zoynal Abedin, Toshihiro Tsuji, Jinho Lee

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Time-developing direct numerical simulations are performed for the combined-convection boundary layers created by imposing aiding and opposing freestreams to the pure natural-convection boundary layer in air along a heated vertical flat plate to clarify their structural characteristics. The numerical results reveal that with a slight increase in freestream velocity, the transition region moves downstream for aiding flow and upstream for opposing flow. This fact correlates well with the existing experimental results showing that the transition delays for aiding flow and quickens for opposing flow in the practical space-developing boundary layer. Thereby, for aiding flow, turbulence characteristics indicate the behavior proceeding to the laminarization of the boundary layer. On the other hand, for opposing flow, the large scale fluid motions are apparent and become larger than those for the pure natural-convection boundary layer with increasing freestream velocity. For the occurrence of such fluid motions, the budgets of turbulent energy and two-point spatial correlations in the turbulent combined-convection boundary layers are also examined. Consequently, it is found in the spatial correlations that the turbulence structures are mainly controlled by fluid motions in the outer region of the boundary layer.

Original languageEnglish
Pages (from-to)3995-4002
Number of pages8
JournalInternational Journal of Heat and Mass Transfer
Volume55
Issue number15-16
DOIs
Publication statusPublished - 2012 Jul 1

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flat plates
boundary layers
Boundary layers
Turbulence
convection
turbulence
Natural convection
free convection
Fluids
fluids
Direct numerical simulation
Convection
direct numerical simulation
budgets
upstream
occurrences
air
Air

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

Cite this

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abstract = "Time-developing direct numerical simulations are performed for the combined-convection boundary layers created by imposing aiding and opposing freestreams to the pure natural-convection boundary layer in air along a heated vertical flat plate to clarify their structural characteristics. The numerical results reveal that with a slight increase in freestream velocity, the transition region moves downstream for aiding flow and upstream for opposing flow. This fact correlates well with the existing experimental results showing that the transition delays for aiding flow and quickens for opposing flow in the practical space-developing boundary layer. Thereby, for aiding flow, turbulence characteristics indicate the behavior proceeding to the laminarization of the boundary layer. On the other hand, for opposing flow, the large scale fluid motions are apparent and become larger than those for the pure natural-convection boundary layer with increasing freestream velocity. For the occurrence of such fluid motions, the budgets of turbulent energy and two-point spatial correlations in the turbulent combined-convection boundary layers are also examined. Consequently, it is found in the spatial correlations that the turbulence structures are mainly controlled by fluid motions in the outer region of the boundary layer.",
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Turbulence characteristics and vortical structures in combined-convection boundary layers along a heated vertical flat plate. / Abedin, Mohammad Zoynal; Tsuji, Toshihiro; Lee, Jinho.

In: International Journal of Heat and Mass Transfer, Vol. 55, No. 15-16, 01.07.2012, p. 3995-4002.

Research output: Contribution to journalArticle

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