Mommert, Michael und Schiepel, Daniel und Schmeling, Daniel und Wagner, Claus (2020) Reversals of coherent structures in turbulent mixed convection. Journal of Fluid Mechanics, 904, A33-1-A33-33. Cambridge University Press. doi: 10.1017/jfm.2020.705. ISSN 0022-1120.
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Offizielle URL: https://doi.org/10.1017/jfm.2020.705
Kurzfassung
Reconfiguration events in turbulent mixed convection, i.e. the superposition of thermal and forced flow contributions, at the two different Richardson numbers Ri=1.5 and Ri=3.7 and similar Rayleigh numbers of Ra≈10^8 are investigated with tomographic particle image velocimetry in combination with local temperature measurements. For both cases, the three-dimensional velocity fields reflect diagonally aligned large-scale circulations (LSC) switching their alignment by rotating their axes around a pivot located at the centre of the LSC, while the temperatures perform a translation movement of the structures in agreement with earlier temperature-based investigations. For the high Ri case, the switching process of the observed spontaneous reconfigurations is induced by a reversing thermal flow contribution while the forced flow contribution is constant. Furthermore, it is shown that a secondary roll structure, which drives the reconfiguration process in Rayleigh–Bénard convection, also exists in mixed convection. However, in the latter, the flow reversals are triggered by different structures which accumulate and release their kinetic energy according to a proper orthogonal decomposition analysis. In contrast, for the low Ri case, the structure formation during continuous reconfigurations is governed by a Taylor- or Görtler-type instability. This means that the forced convection substantially affects the reconfiguration mechanism of these structures. Therefore, the reconfigurations cannot be described by a simple superposition of structures associated with the two flow contributions as for the high Ri.
elib-URL des Eintrags: | https://elib.dlr.de/134154/ | ||||||||||||||||||||
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Dokumentart: | Zeitschriftenbeitrag | ||||||||||||||||||||
Titel: | Reversals of coherent structures in turbulent mixed convection | ||||||||||||||||||||
Autoren: |
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Datum: | 13 Oktober 2020 | ||||||||||||||||||||
Erschienen in: | Journal of Fluid Mechanics | ||||||||||||||||||||
Open Access: | Ja | ||||||||||||||||||||
Gold Open Access: | Nein | ||||||||||||||||||||
In SCOPUS: | Ja | ||||||||||||||||||||
In ISI Web of Science: | Ja | ||||||||||||||||||||
Band: | 904 | ||||||||||||||||||||
DOI: | 10.1017/jfm.2020.705 | ||||||||||||||||||||
Seitenbereich: | A33-1-A33-33 | ||||||||||||||||||||
Herausgeber: |
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Verlag: | Cambridge University Press | ||||||||||||||||||||
ISSN: | 0022-1120 | ||||||||||||||||||||
Status: | veröffentlicht | ||||||||||||||||||||
Stichwörter: | buoyancy-driven instability, convection in cavities, turbulent convection | ||||||||||||||||||||
HGF - Forschungsbereich: | Luftfahrt, Raumfahrt und Verkehr | ||||||||||||||||||||
HGF - Programm: | Verkehr | ||||||||||||||||||||
HGF - Programmthema: | Schienenverkehr | ||||||||||||||||||||
DLR - Schwerpunkt: | Verkehr | ||||||||||||||||||||
DLR - Forschungsgebiet: | V SC Schienenverkehr | ||||||||||||||||||||
DLR - Teilgebiet (Projekt, Vorhaben): | V - NGT BIT (alt) | ||||||||||||||||||||
Standort: | Göttingen | ||||||||||||||||||||
Institute & Einrichtungen: | Institut für Aerodynamik und Strömungstechnik > Bodengebundene Fahrzeuge | ||||||||||||||||||||
Hinterlegt von: | Mommert, Michael | ||||||||||||||||||||
Hinterlegt am: | 19 Okt 2020 12:02 | ||||||||||||||||||||
Letzte Änderung: | 24 Okt 2023 10:50 |
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