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Postprint
DOI: 10.5445/IR/1000087741
Frei zugänglich ab 29.09.2019

Rearrangement of secondary vortices over spanwise heterogeneous roughness

Stroh, Alexander; Forooghi, Pourya; Frohnapfel, Bettina

Abstract:
A spanwise heterogeneity of roughness is known to lead to the formation of large-scale secondary motions. In the present work the secondary motions are investigated based on the data sets extracted from direct numerical simulations (DNS) of fully developed turbulent open channel flow where spanwise-alternating streamwise stripes of rough and smooth surfaces with variation of the smooth surface elevation are introduced. In order to study the character of the secondary flow structures, the resultant flow fields are further analysed by means of instantaneous flow topology and by decomposition of the bulk mean velocity into its contribution parts. It is found that the wall-normal position of the smooth stripes significantly alters the secondary motion topology and strength of the motions. This alteration is also reflected in the fact that different volume flow rates are realized for different elevation heights of the smooth surface although the effective friction Reynolds numbers is kept constant.


Zugehörige Institution(en) am KIT Institut für Strömungsmechanik (ISTM)
Publikationstyp Proceedingsbeitrag
Jahr 2018
Sprache Englisch
Identifikator URN: urn:nbn:de:swb:90-877413
KITopen-ID: 1000087741
Erschienen in 12th International ERCOFTAC Symposium on Engineering Turbulence Modelling and Measurements (ETMM12), Montpellier, F, September 26-28, 2018
Schlagworte turbulent channel flow, inhomogeneous roughness, secondary flows
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