PMID: 12786277Jun 6, 2003Paper

Drag reduction by polymers in turbulent channel flows: Energy redistribution between invariant empirical modes

Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
Elisabetta De AngelisItamar Procaccia

Abstract

We address the phenomenon of drag reduction by a dilute polymeric additive to turbulent flows, using direct numerical simulations (DNS) of the FENE-P model of viscoelastic flows. It had been amply demonstrated that these model equations reproduce the phenomenon, but the results of DNS were not analyzed so far with the goal of interpreting the phenomenon. In order to construct a useful framework for the understanding of drag reduction we initiate in this paper an investigation of the most important modes that are sustained in the viscoelastic and Newtonian turbulent flows, respectively. The modes are obtained empirically using the Karhunen-Loéve decomposition, allowing us to compare the most energetic modes in the viscoelastic and Newtonian flows. The main finding of the present study is that the spatial profile of the most energetic modes is hardly changed between the two flows. What changes is the energy associated with these modes, and their relative ordering in the decreasing order from the most energetic to the least. Modes that are highly excited in one flow can be strongly suppressed in the other, and vice versa. This dramatic energy redistribution is an important clue to the mechanism of drag reduction as is proposed in ...Continue Reading

References

Nov 3, 2001·Physical Review Letters·R GovindarajanI Procaccia
Dec 12, 2001·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·E BalkovskyV Lebedev
Apr 24, 2002·Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics·I AradI Procaccia
Mar 15, 2003·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Rama GovindarajanA Sameen
Mar 15, 2003·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Victor S L'vovVasil Tiberkevich

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Citations

Jul 13, 2004·Physical Review Letters·Victor S L'vovVasil Tiberkevich
Sep 28, 2004·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Roberto BenziItamar Procaccia
Dec 17, 2004·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Elisabetta De AngelisVasil Tiberkevich
May 21, 2005·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Guido BoffettaAndrea Mazzino
Oct 4, 2003·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Roberto Benzi, Itamar Procaccia
Dec 20, 2003·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Victor S L'vovVasil Tiberkevich

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