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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, F-75231 Paris 05,France Univ Paris 06 Paris France 05 er, Lab Phys Stat, F-75231 Paris 05,France Univ Paris 07, CNRS, Ecole Normale Super, Lab Phys Stat, F-75231 Paris, France Univ Paris 07 Paris France F-75231 Lab Phys Stat, F-75231 Paris, France
Titolo Testata:
JOURNAL OF FLUID MECHANICS
, volume: 444, anno: 2001,
pagine: 151 - 174
SICI:
0022-1120(20011010)444:<151:AEOTAO>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
NAVIER-STOKES EQUATIONS; STAGNATION-POINT FLOW; 3-DIMENSIONAL TURBULENCE; STRETCHED VORTICES; ISOTROPIC TURBULENCE; INTENSE VORTICITY; VORTEX TUBES; 4-ROLL 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, F-75231 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. 151-174

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 four-roll 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 Re-c = 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 two-dimensionalization 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 21/09/20 alle ore 09:38:42