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Direct numerical simulations of the turbulent convection and thermal radiation in a Rayleigh-Bénard cell

Czarnota, Tomasz und Wagner, Claus (2011) Direct numerical simulations of the turbulent convection and thermal radiation in a Rayleigh-Bénard cell. Seventh International Symposium on Turbulence and Shear Flow Phenomema, 28.-31. Jul. 2011, Ottawa, Canada.

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Offizielle URL: http://www.tsfp7.org/papers.php

Kurzfassung

We perform direct numerical simulations (DNS) of turbulent Rayleigh-Bénard convection coupled with surface-to-surface radiation in a rectangular enclosure filled with air to investigate whether this interaction influences the heat transfer, temperature distribution and the flow structures. To do so, horizontal solid plates with finite conductivity are employed for the considered Rayleigh-Bénard cell. Such boundary conditions allow local variations of the temperature at the hot and cold interfaces due to their interaction with the fluid and surface radiation. In order to investigate the maximum effect of those boundary conditions, both interfaces are treated as a blackbody ε=1 and the cell is filled with a radiatively non-participating fluid (Prandtl number Pr=0.7). The effects of radiation for highly conducting plates are shown and compared to the case where radiation is neglected. It is found that due to highly conducting plates the mean temperature at the interfaces changes only 0.04% from the one of the infinite conductive plates. Furthermore, we observe that due to surface-to-surface radiation coupled with highly conducting plates, the mean temperature at the interfaces changes 0.1% at the interfaces and 0.2% in the bulk. It is shown that the temperature at the hot interface tends to decrease due to the radiative heat loss while the temperature at the cold interface slightly increases. Apart from that, we observe small changes in the temperature distribution at the interfaces due to surface-to-surface radiation. We notice that the highest temperatures at the top interface appear in the middle and the values steadily decrease towards the edges. Additionally, we observe a small drop of the convective Nusselt number and little variations of the temperature distribution at the interfaces. Finally, it is shown that all mentioned variations caused by heat radiation between interfaces are too small to visibly change the large scale flow structures when highly conducting plates are employed. It is also shown that in the non-radiation case of poorly conducting plates the heat transfer and the temperature variations at the interfaces are influenced significantly.

Dokumentart:Konferenzbeitrag (Vortrag, Paper)
Titel:Direct numerical simulations of the turbulent convection and thermal radiation in a Rayleigh-Bénard cell
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Czarnota, TomaszTomasz.Czarnota@dlr.de
Wagner, ClausClaus.Wagner@dlr.de
Datum:2011
Referierte Publikation:Nein
In ISI Web of Science:Nein
Name der Reihe:Conference Proceedings Online
Status:veröffentlicht
Stichwörter:DNS, Rayleigh-Bénard, convection, radiation
Veranstaltungstitel:Seventh International Symposium on Turbulence and Shear Flow Phenomema
Veranstaltungsort:Ottawa, Canada
Veranstaltungsart:internationale Konferenz
Veranstaltungsdatum:28.-31. Jul. 2011
HGF - Forschungsbereich:Luftfahrt, Raumfahrt und Verkehr
HGF - Programm:Luftfahrt
HGF - Programmthema:Starrflügler
DLR - Schwerpunkt:Luftfahrt
DLR - Forschungsgebiet:L AR - Starrflüglerforschung
DLR - Teilgebiet (Projekt, Vorhaben):L - Flugphysik
Standort: Göttingen
Institute & Einrichtungen:Institut für Aerodynamik und Strömungstechnik > Fluidsysteme
Hinterlegt von: Tomasz Czarnota
Hinterlegt am:19 Okt 2011 14:15
Letzte Änderung:12 Dez 2013 21:18

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