[en] Numerical simulations of turbulent polymer solutions using the FENE-P model are used to characterize the action of polymers on turbulence in drag-reduced flows. The energetics of turbulence is investigated by correlating the work done by polymers on the flow with turbulent structures. Polymers are found to store and to release energy to the flow in a well-organized manner. The storage of energy occurs around near-wall vortices as has been anticipated for a long time. Quite unexpectedly, coherent release of energy is observed in the very near-wall region. Large fluctuations of polymer work are shown to re-energize decaying streamwise velocity fluctuations in highspeed streaks just above the viscous sublayer. These distinct behaviours are used to propose an autonomous regeneration cycle of polymer wall turbulence, in the spirit of Jimenez & Pinelli (1999).
Disciplines :
Chemical engineering Mechanical engineering
Author, co-author :
Dubief, Yves; Center for Turbulence Research, Stanford University
White, Christopher M.; Stanford University > Mechanical Engineering Department
Terrapon, Vincent ; Stanford University > Mechanical Engineering Department
Shaqfeh, Eric S.G.; Stanford University > Mechanical Engineering Department, Department of Chemical Engineering
Moin, Parviz; Center for Turbulence Research, Stanford University > Mechanical Engineering Department
Lele, Sanjiva K.; Stanford University > Mechanical Engineering Department, Department of Aeronautics and Astronautics
Language :
English
Title :
On the coherent drag-reducing and turbulence-enhancing behaviour of polymers in wall flows
Publication date :
2004
Journal title :
Journal of Fluid Mechanics
ISSN :
0022-1120
eISSN :
1469-7645
Publisher :
Cambridge University Press, New York, United States - New York
Volume :
514
Pages :
271-280
Peer reviewed :
Peer Reviewed verified by ORBi
Name of the research project :
Friction Drag Reduction Program
Funders :
DARPA - Defense Advanced Research Projects Agency [US-VA] [US-VA]
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