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Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)

Coherent structures and secondary motions in open/closed duct flow

REFERENT: Dr.-Ing. Yoshiyuki Sakai, Institute for Hydromechanics, KIT, Karlsruhe
TITEL: Coherent structures and secondary motions in open/closed duct flow
ZEIT: 14th December 2016, 10.00 Uhr Vortragsbeginn
ORT: DLR Göttingen, Adolf-Busemann-Raum (Haus 7, EG)
 
Fluid flow through a straight rectangular duct with/without free surface is known to exhibit turbulence-induced secondary motions, also known as "secondary motion of Prandtl's second kind''. The intensity of such cross-stream flow has a small amplitude (only few percent of the bulk velocity), but with a large consequence in momentum, heat and mass transports. A series of fully-resolved pseudo-spectral direct numerical simulations were performed with a range of Reynolds number (Reb) and aspect ratio (A), in order for in-depth secondary flow generation mechanism, the Re-dependence and the A-dependence studies to be carried out. Our main focus for the investigations were continuously placed upon the preferential locations and dynamics of the turbulent coherent structures in duct flow, and their statistical footprints in the time-averaged secondary flow phenomena.

 





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