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Quantifying near-wall coherent structures in turbulent convection

Gunasegarane, G. S. and Puthenveettil, Baburaj A. and Agrawal, Yogesh K. and Schmeling, Daniel and Bosbach, Johannes and Arakeri, Jaywant H. (2011) Quantifying near-wall coherent structures in turbulent convection. In: Bulletin of the American Physical Society, 64th Annual Meeting of the APS Division of Fluid Dynamics, Volume 56, Number 18, Vol.56 (18), pp. 114-115. 64th Annual Meeting of the APS Division of Fluid Dynamics, 20. - 22. Nov. 2011, Baltimore, USA. ISSN 0003-0503

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Official URL: http://meetings.aps.org/link/BAPS.2011.DFD.E5.8

Abstract

We present planforms of line plumes formed on horizontal surfaces in turbulent convection, along with the length of near-wall 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, 6, 602). Using geometric constraints on the relations for the mean plume spacings, we obtain expressions for the total length of these near-wall plumes 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 a 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. 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.

Item URL in elib:https://elib.dlr.de/81933/
Document Type:Conference or Workshop Item (Speech)
Title:Quantifying near-wall coherent structures in turbulent convection
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Gunasegarane, G. S.Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai, IndiaUNSPECIFIED
Puthenveettil, Baburaj A.Department od Applied Mechanics, Indian Institute of Technology Madras, Chennai, IndiaUNSPECIFIED
Agrawal, Yogesh K.Department of Mechanical Engineering, National Institute of Technology, Durgapur, IndiaUNSPECIFIED
Schmeling, Danieldaniel.schmeling (at) dlr.deUNSPECIFIED
Bosbach, Johannesjohannes.bosbach (at) dlr.deUNSPECIFIED
Arakeri, Jaywant H.Department of Mechanical Engineering, Indian Institute of Science, Bangalore, IndiaUNSPECIFIED
Date:November 2011
Journal or Publication Title:Bulletin of the American Physical Society, 64th Annual Meeting of the APS Division of Fluid Dynamics, Volume 56, Number 18
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:Vol.56
Page Range:pp. 114-115
Series Name:Bulletin of the American Physical Society
ISSN:0003-0503
Status:Published
Keywords:natural convection, plumes
Event Title:64th Annual Meeting of the APS Division of Fluid Dynamics
Event Location:Baltimore, USA
Event Type:international Conference
Event Dates:20. - 22. Nov. 2011
Organizer:American Physical Society
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Terrestrial Vehicles (old)
DLR - Research area:Transport
DLR - Program:V BF - Bodengebundene Fahrzeuge
DLR - Research theme (Project):V - Next Generation Train (old)
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Fluid Systems
Deposited By: Schmeling, Dr Daniel
Deposited On:15 Apr 2013 16:14
Last Modified:12 Dec 2013 22:02

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