TY - JOUR
T1 - Effects of freestream on the characteristics of thermally-driven boundary layers along a heated vertical flat plate
AU - Abedin, Mohammad Zoynal
AU - Tsuji, Toshihiro
AU - Lee, Jinho
N1 - Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2012/8
Y1 - 2012/8
N2 - Time-developing thermally-driven boundary layers created by imposing aiding and opposing freestreams on the natural-convection boundary layer in water along a heated vertical flat plate have been examined with a direct numerical simulation to clarify their transition and turbulence behaviors. The numerical results for aiding flow reveal that the transition begins at a thick laminar boundary layer due to the delay of the transition and large-scale vortexes centering on the spanwise direction are followed, while, for opposing flow, the transition begins at a thin laminar boundary layer due to the quickening of the transition and relatively small-scale vortexes are generated with the progress of transition. To improve the significance of the present numerical results, the association of turbulence statistics between time- and space-developing flows has been investigated. Consequently, the numerical results for time-developing flow are converted to those for space-developing flow through the integral thickness of the velocity boundary layer for pure natural convection, and thus the regimes of boundary layer flows can be quantitatively assessed. Moreover, the turbulence statistics and the flow structures in the thermally-driven boundary layers are also presented.
AB - Time-developing thermally-driven boundary layers created by imposing aiding and opposing freestreams on the natural-convection boundary layer in water along a heated vertical flat plate have been examined with a direct numerical simulation to clarify their transition and turbulence behaviors. The numerical results for aiding flow reveal that the transition begins at a thick laminar boundary layer due to the delay of the transition and large-scale vortexes centering on the spanwise direction are followed, while, for opposing flow, the transition begins at a thin laminar boundary layer due to the quickening of the transition and relatively small-scale vortexes are generated with the progress of transition. To improve the significance of the present numerical results, the association of turbulence statistics between time- and space-developing flows has been investigated. Consequently, the numerical results for time-developing flow are converted to those for space-developing flow through the integral thickness of the velocity boundary layer for pure natural convection, and thus the regimes of boundary layer flows can be quantitatively assessed. Moreover, the turbulence statistics and the flow structures in the thermally-driven boundary layers are also presented.
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U2 - 10.1016/j.ijheatfluidflow.2012.03.003
DO - 10.1016/j.ijheatfluidflow.2012.03.003
M3 - Article
AN - SCOPUS:84863879800
VL - 36
SP - 92
EP - 100
JO - Heat Fluid Flow
JF - Heat Fluid Flow
SN - 0142-727X
ER -