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SPECTRAL PROPERTIES OF THE TURBULENT FLOW OF A VISCOELASTIC FLUID FOR REDUCED DRAG

L. Thais
Unite de Mecanique de Lille, Polytech'Lille, Universite de Lille, Cite Scientifique, Av. Paul Langevin, 59650 Villeneuve d'Ascq, France

Thomas B. Gatski
Institut Pprime, CNRS-Université de Poitiers-ENSMA F86036 Poitiers cedex, France; Center for Coastal Physical Oceanography and Ocean, Earth and Atmospheric Sciences Old Dominion University, Norfolk, Virginia 23529 USA

Gilmar Mompean
Unite de Mecanique de Lille, Polytech'Lille, Universite de Lille, Cite Scientifique, Av. Paul Langevin, 59650 Villeneuve d'Ascq, France

Abstrakt

In the present study, direct numerical simulation (DNS) results of fully developed turbulent channel flows of a viscoelastic fluid modeled as a polymer dilution in a Newtonian solvent are analyzed. The analysis is focused on the spectral properties of the turbulent stress and vorticity fields in order to contrast the properties of turbulence of viscoelastic and Newtonian fluids, and to quantify the effects of increased elasticity on the spectral behavior. The simulation results coupled with the spectral analysis justmentioned can be useful in further assessing the two classes of explanations that have been proposed by Lumley (1969) and De Gennes (1986) for the occurrence of polymer drag reduction.