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Turbulent convection in a Rayleigh-Bénard cell with solid horizontal plates of finite conductivity

Czarnota, Tomasz and Wagner, Claus (2011) Turbulent convection in a Rayleigh-Bénard cell with solid horizontal plates of finite conductivity. In: ERCOFTAC Series Direct and Large-Eddy Simulation VIII, Vol. 1 (6). Springer Netherlands. pp. 371-376. ISBN 978-94-007-2481-5 (Print) 978-94-007-2482-2 (Online). ISSN 1382-4309 (Print)

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Official URL: http://www.springerlink.com/content/mv02486627282542/

Abstract

Turbulent Rayleigh-Bénard convection (RBC) is one of the classical problems of fluid dynamics. In spite of the great effort made in the past to understand the complex physical mechanisms in this type of flow, there are still many open questions which must be answered. In order to understand the effect of conductive horizontal plates on the flow structure in a Rayleigh-Bénard cell the differences between finite and infinite conductivity of the horizontal plates were the aim of many experimental and numerical studies, see (Brown et al., 2005; Johnston and Doering, 2009; Verzicco and Sreenivasan, 2008). Actually, the horizontal plates are assumed to be isothermal in most numerical simulations while they are conductive in experiments. Even more, the finite conductivity of the plates is one explanation for discrepancies between results obtained in experiments and numerical simulations. A fixed temperature boundary condition corresponds to infinite thermal conductivity of the plates while an imposed heat flux models poorly conducting plates. The effect of these two boundary conditions was recently compared by (Verzicco and Sreenivasan, 2008). Their studies indicated that the heat transfer is suppressed for Ra>109 in simulations with plates of finite conductivity whereas for lower Ra the two cases leed to similar flows which agree with observations by (Johnston and Doering, 2009). They concluded that below Ra≈1010 the plate conductivity plays no significant role in the Nu∼Ra 2/7 scaling. Nevertheless, the results of (Verzicco and Sreenivasan, 2008) as well as those of (Johnston and Doering, 2009) refer to a cell with infinitely thin plates while the finite thickness of the plates is considered in our simulations. In the present study the scaling exponent β in the Nusselt-Rayleigh relation, i.e. Nu∼Ra β obtained for the cell with highly conducting aluminium plates is similar as those obtained by (Kaczorowski and Wagner, 2007), who studied RBC in the same convection cell and for the same Pr and similar Ra. However, the scaling exponent obtained for the cell with poorly conducting plexiglas plates is found to be slightly lower than those obtained by (Kaczorowski and Wagner, 2007).

Document Type:Contribution to a Collection
Additional Information:DOI: 10.1007/978-94-007-2482-2_59
Title:Turbulent convection in a Rayleigh-Bénard cell with solid horizontal plates of finite conductivity
Authors:
AuthorsInstitution or Email of Authors
Czarnota, TomaszTomasz.Czarnota@dlr.de
Wagner, ClausClaus.Wagner@dlr.de
Date:2011
Journal or Publication Title:ERCOFTAC Series
Refereed publication:Yes
Volume:Vol. 1
Page Range:pp. 371-376
Editors:
EditorsEmail
Kuerten, HansDepartment of Mechanical Engineering, Eindhoven University of Technology
Geurts, BernardFac. Mathematical Sciences, University of Twente
Armenio, VincenzoDipto. Ingegneria Civile e Ambientale, Università di Trieste
Fröhlich, JochenInstitute of Fluid Mechanics, Inst. Energiemaschinen und, Technical University of Dresden
Publisher:Springer Netherlands
Series Name:Direct and Large-Eddy Simulation VIII
ISSN:1382-4309 (Print)
ISBN:978-94-007-2481-5 (Print) 978-94-007-2482-2 (Online)
Status:Published
Keywords:DNS, Rayleigh-Bénard cell, turbulent convection
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Terrestrial Vehicles
DLR - Research area:Transport
DLR - Program:V BF - Bodengebundene Fahrzeuge
DLR - Research theme (Project):V - Fahrzeugenergiesysteme (old)
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Fluid Systems
Deposited By: Tomasz Czarnota
Deposited On:14 Dec 2011 09:06
Last Modified:12 Dec 2013 21:26

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