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The influence of non-Oberbeck-Boussinesq effects and rotation on turbulent Rayleigh-Bénard convection

Horn, Susanne and Shishkina, Olga and Wagner, Claus (2011) The influence of non-Oberbeck-Boussinesq effects and rotation on turbulent Rayleigh-Bénard convection. TSFP7, 28. -31. Jul. 2011, Ottawa, Canada.

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Abstract

The influence of rotation on turbulent Rayleigh-Bénard convection in combination with non-Oberbeck-Boussinesq (NOB) effects is investigated by means of three-dimensional direct numerical simulations (DNS). For this purpose the impact of temperature dependent material properties is studied in glycerol with a Prandtl number of Pr = 2547.9 within a range of Rayleigh numbers of 10^5 ≤ Ra ≤ 10^8, and in water with Pr = 4.38 at Ra = 10^8, both under no rotation and superimposed with rotation within a Rossby number range of 0.3 ≤ Ro ≤ 3.0. The generated flow fields are analysed with respect to deviations from the Oberbeck-Boussinesq (OB) case. We obtain a breakdown of the top-bottom symmetry, that is, different boundary layer thicknesses, modified mean temperature profiles including an increase of the centre temperature and asymmetric velocity flow patterns for glycerol as well as for water in the non-rotating case. When the Rayleigh-Bénard cell is rotated, NOB effects decrease with increasing rotation rate, but are still significant. In particular they lead to a smaller gradient of the temperature within the bulk. The Nusselt number Nu in the non-rotating NOB cases slightly decreases, while it slightly increases in the rotating ones. However, the change in Nu remains within a few percent for all cases.

Document Type:Conference or Workshop Item (Speech, Paper)
Title:The influence of non-Oberbeck-Boussinesq effects and rotation on turbulent Rayleigh-Bénard convection
Authors:
AuthorsInstitution or Email of Authors
Horn, Susannesusanne.horn@dlr.de
Shishkina, OlgaUNSPECIFIED
Wagner, ClausUNSPECIFIED
Date:2011
Status:Published
Keywords:Rayleigh-Bénard convection, non-Oberbeck-Boussinsq effects, rotation
Event Title:TSFP7
Event Location:Ottawa, Canada
Event Type:international Conference
Event Dates:28. -31. Jul. 2011
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: Susanne Horn
Deposited On:17 Jan 2012 12:21
Last Modified:12 Dec 2013 21:18

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