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The effect of spanwise heterogeneous surfaces on mixed convection in turbulent channels

Schäfer, Kay ORCID iD icon 1; Frohnapfel, Bettina ORCID iD icon 1; Mellado, Juan Pedro
1 Institut für Strömungsmechanik (ISTM), Karlsruher Institut für Technologie (KIT)

Abstract:

Turbulent mixed convection in channel flows with heterogeneous surfaces is studied using direct numerical simulations. The relative importance of buoyancy and shear effects, characterised by the bulk Richardson number $\textit{Ri}_{b}$, is varied in order to cover the flow regimes of forced, mixed and natural convection, which are associated with different large-scale flow organisations. The heterogeneous surface consists of streamwise-aligned ridges, which are known to induce secondary motion in the case of forced convection. The large-scale streamwise rolls emerging under smooth-wall mixed convection conditions are significantly affected by the heterogeneous surfaces and their appearance is considerably reduced for dense ridge spacings. It is found that the formation of these rolls requires larger buoyancy forces than over smooth walls due to the additional drag induced by the ridges. Therefore, the transition from forced convection structures to rolls is delayed towards larger $\textit{Ri}_{b}$ for spanwise heterogeneous surfaces. The influence of the heterogeneous surface on the flow organisation of mixed convection is particularly pronounced in the roll-to-cell transition range, where ridges favour the transition to convective cells at significantly lower $\textit{Ri}_{b}$. ... mehr


Verlagsausgabe §
DOI: 10.5445/IR/1000152725
Veröffentlicht am 15.11.2022
Originalveröffentlichung
DOI: 10.1017/jfm.2022.773
Scopus
Zitationen: 2
Web of Science
Zitationen: 1
Dimensions
Zitationen: 2
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Strömungsmechanik (ISTM)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 10.11.2022
Sprache Englisch
Identifikator ISSN: 0022-1120, 1469-7645
KITopen-ID: 1000152725
Erschienen in Journal of Fluid Mechanics
Verlag Cambridge University Press (CUP)
Band 950
Seiten Art.Nr. A22
Vorab online veröffentlicht am 24.10.2022
Nachgewiesen in Dimensions
Web of Science
Scopus
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