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Length of near-wall plumes in turbulent convection

Puthenveettil, Baburaj A. and Gunasegarane, G. S. and Agrawal, Yogesh K. and Schmeling, Daniel and Bosbach, Johannes and Arakeri, Jaywant H. (2011) Length of near-wall plumes in turbulent convection. Journal of Fluid Mechanics, Vol. 6, pp. 335-364. Cambridge University Press. DOI: 10.1017/jfm.2011.319. ISSN 0022-1120.

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Official URL: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8384309&fulltextType=RA&fileId=S0022112011003193

Abstract

We present planforms of line plumes formed on horizontal surfaces in turbulent convection, along with the length of line plumes measured from these planforms, in a six decade range of Rayleigh numbers (10^5 < Ra < 10^11) and at three Prandtl numbers (Pr= 0.7, 5.2, 602). Using geometric constraints on the relations for the mean plume spacings, we obtain expressions for the total length of near-wall plumes on horizontal surfaces in turbulent convection. The plume length per unit area (L_p / A), made dimensionless by the near-wall length scale in turbulent convection (Z_w), remains constant for a given fluid. The Nusselt number is shown to be directly proportional to L_p H/ A for a given fluid layer of height H. The increase in Pr has a weak influence in decreasing L_p / A. These expressions match the measurements, thereby showing that the assumption of laminar natural convection boundary layers in turbulent convection is consistent with the observed total length of line plumes. We then show that similar relationships are obtained based on the assumption that the line plumes are the outcome of the instability of laminar natural convection boundary layers on the horizontal surfaces.

Document Type:Article
Additional Information:Published online: 20. September 2011
Title:Length of near-wall plumes in turbulent convection
Authors:
AuthorsInstitution or Email of Authors
Puthenveettil, Baburaj A.Department od Applied Mechanics, Indian Institute of Technology Madras, Chennai, India
Gunasegarane, G. S.Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai, India
Agrawal, Yogesh K.Department of Mechanical Engineering, National Institute of Technology, Durgapur, India
Schmeling, DanielUNSPECIFIED
Bosbach, JohannesUNSPECIFIED
Arakeri, Jaywant H.Department of Mechanical Engineering, Indian Institute of Science, Bangalore, India
Date:2011
Journal or Publication Title:Journal of Fluid Mechanics
Refereed publication:Yes
In Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:Vol. 6
DOI:10.1017/jfm.2011.319
Page Range:pp. 335-364
Publisher:Cambridge University Press
ISSN:0022-1120
Status:Published
Keywords:buoyant boundary layers, plumes/thermals, turbulent convection
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Flight Physics
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Fluid Systems
Deposited By: Daniel Schmeling
Deposited On:23 Sep 2011 11:15
Last Modified:12 Dec 2013 21:16

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