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Titolo: An experiment on two aspects of the interaction between strain and vorticity
Autore: Andreotti, B; Douady, S; Couder, Y;
 Indirizzi:
 Univ Paris 06, CNRS, Ecole Normale Super, Lab Phys Stat, F75231 Paris 05,France Univ Paris 06 Paris France 05 er, Lab Phys Stat, F75231 Paris 05,France Univ Paris 07, CNRS, Ecole Normale Super, Lab Phys Stat, F75231 Paris, France Univ Paris 07 Paris France F75231 Lab Phys Stat, F75231 Paris, France
 Titolo Testata:
 JOURNAL OF FLUID MECHANICS
,
volume: 444,
anno: 2001,
pagine: 151  174
 SICI:
 00221120(20011010)444:<151:AEOTAO>2.0.ZU;27
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 NAVIERSTOKES EQUATIONS; STAGNATIONPOINT FLOW; 3DIMENSIONAL TURBULENCE; STRETCHED VORTICES; ISOTROPIC TURBULENCE; INTENSE VORTICITY; VORTEX TUBES; 4ROLL MILL; SHEAR FLOWS; DYNAMICS;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Physical, Chemical & Earth Sciences
 Engineering, Computing & Technology
 Citazioni:
 46
 Recensione:
 Indirizzi per estratti:
 Indirizzo: Andreotti, B Univ Paris 06, CNRS, Ecole Normale Super, Lab Phys Stat, 24 Rue Lhomond, F75231 Paris 05, France Univ Paris 06 24 Rue Lhomond Paris France 05 aris 05, France



 Citazione:
 B. Andreotti et al., "An experiment on two aspects of the interaction between strain and vorticity", J FLUID MEC, 444, 2001, pp. 151174
Abstract
Presented here are two results concerning the interaction between vorticity and strain. Both are obtained experimentally by investigating the hyperbolic flow created in Taylor's fourroll mill. It is first shown that this pure straining flow becomes intrinsically unstable through a supercritical bifurcation to form an array of counterrotating vortices aligned in the stretching direction. The dimensionless parameter characterizing the flow is theinternal Reynolds number Re = gamma Delta (2)/nu based on the velocity gradient gamma and on the gap between the rollers Delta, and the threshold value is Rec = 17. Near the threshold, the transverse velocity profiles of these vortices are in excellent agreement with those predicted by the theory of Kerr & Dold (1994) in the case of an infinite hyperbolic flow. A second result is obtained at high Reynolds number. Measurements of the velocity profile in the direction parallel to the vortices show that the velocity gradient (the stretching) is systematically weaker inside the vortices than elsewhere. This demonstrates experimentally the existence of a negative feedback of rotation on stretching. This effect is ascribed to the twodimensionalization due to the vortex fast rotation. An implication of these results for turbulent flows is a nonlinear limitation of the vorticity stretching, an effect characterized recently by Ohkitani 1998.
ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 24/10/20 alle ore 11:57:37