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Analysis of sheet-like thermal plumes in turbulent Rayleigh–Bénard convection

Shishkina, Olga and Wagner, Claus (2008) Analysis of sheet-like thermal plumes in turbulent Rayleigh–Bénard convection. Journal of Fluid Mechanics, 599, pp. 383-404. Cambridge University Press. doi: 10.1017/S002211200800013X. ISSN 0022-1120.

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Official URL: https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/analysis-of-sheetlike-thermal-plumes-in-turbulent-rayleighbenard-convection/41C88043FC2D3F6A04A979C4491FE667#


Sheet-like thermal plumes are investigated using time-dependent and three-dimensional flow fields obtained from direct numerical simulations and well-resolved large-eddy simulations of turbulent Rayleigh–Bénard convection in water (Prandtl number Pr=5.4) in a cylindrical container with the aspect ratio Γ=1 and for the Rayleigh numbers Ra=2×109 and 2×1010. To analyse quantitatively the physical properties of the sheet-like thermal plumes and the turbulent background and to obtain the temperature threshold which separates these two different flow regions, the temperature dependences of the conditionally averaged local heat flux, thermal dissipation rate and selected components of the velocity and vorticity fields are studied. It is shown that the sheet-like plumes are characterized by high values of the local heat flux and relatively large absolute values of the vertical components of the vorticity and velocity fields. The borders of these plumes are indicated by large values of the thermal dissipation rate and large absolute values of the horizontal vorticity components. In contrast to the sheet-like thermal plumes, the turbulent background is characterized by low values of the thermal dissipation rate, local heat flux and vertical vorticity component. The highest values of the local heat flux and the highest absolute values of the vertical vorticity component are found in the regions where the sheet-like plumes strike against each other. Fluid swirling at these places forms the stems of the mushroom-like thermal plumes which develop in the bulk of the Rayleigh–Bénard cell. Further, formulae to calculate the curvature, thickness and length of the plumes are introduced. Geometrical properties such as plume area, diameter, curvature, thickness and aspect ratio together with the physical properties of the sheet-like plumes such as temperature, heat flux, thermal dissipation rate, velocity and vorticity are investigated.

Item URL in elib:https://elib.dlr.de/53690/
Document Type:Article
Title:Analysis of sheet-like thermal plumes in turbulent Rayleigh–Bénard convection
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Wagner, ClausUNSPECIFIEDhttps://orcid.org/0000-0003-2273-0568UNSPECIFIED
Date:6 March 2008
Journal or Publication Title:Journal of Fluid Mechanics
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 383-404
EditorsEmailEditor's ORCID iDORCID Put Code
Publisher:Cambridge University Press
Keywords:Rayleigh-Benard convection, thermal sheet-like plumes, Direct Numerical Simulations, Large-Eddy Simulations
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: Shishkina, PD Dr. habil. Olga
Deposited On:25 Mar 2008
Last Modified:21 Sep 2023 12:45

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