The 125th anniversary of Osborne Reynolds’ seminal publication on the transition to turbulence in pipe flow offers an opportunity to survey our understanding of the nature of the transition. Dynamical systems concepts, computational methods and dedicated experiments have helped to elucidate some of Reynolds’ observations and to extract new quantitative characteristics of the transition. This in...

BACKGROUND Framingham-based and Reynolds Risk scores for cardiovascular disease (CVD) prediction have not been directly compared in an independent validation cohort. METHODS AND RESULTS We selected a case-cohort sample of the multiethnic Women's Health Initiative Observational Cohort, comprising 1722 cases of major CVD (752 myocardial infarctions, 754 ischemic strokes, and 216 other CVD death...

The Log-Poisson phenomenological description of the turbulent energy cascade is evoked to discuss high-order statistics of velocity derivatives and the mapping between their probability distribution functions at different Reynolds numbers. The striking confirmation of theoretical predictions suggests that numerical solutions of the flow obtained at low/moderate Reynolds numbers can play an impo...

The stability of the axisymmetric Burgers vortex solution of the Navier-Stokes equations to two-dimensional perturbations is studied numerically up to Reynolds numbers, R = 1’/2 VU, of order 10”. No unstable eigenmodes for azimuthal mode numbers n= I ,..., 10 are found in this range of Reynolds numbers. Increasing the Reynolds number has a stabilizing effect on the vortex. 0 199.5 American Inst...

flow structure and heat transfer characteristics around two-equal in-tandem square cylinders in the two dimensional laminar and turbulent flow regimes are simulated numerically for reynolds and prandtl numbers, re=1-1×10 5 , pr=0.71, respectively. the investigation is based on an implicit finite volume scheme for integrating the unsteady navier-stokes equations and use of standard κ-ε model to ...

The Lighthill acoustic analogy approach combined with Reynolds-averaged Navier Stokes is used to predict the sound generated by unsteady viscous ow past a circular cylinder assuming a correlation length of ten cylinder diameters. The twodimensional unsteady ow eld is computed using two NavierStokes codes at a low Mach number over a range of Reynolds numbers from 100 to 5 million. Both laminar o...

A closure for the compressible portion of the pressure-strain covariance is developed. It is shown that, within the context of a pressure-strain closure assumption linear in the Reynolds stresses, an expression for the pressure-dilatation can be used to construct a representation for the pressure-strain. Additional closures for the unclosed terms in the Favré-Reynolds stress equations involving...

The Lighthill acoustic analogy approach combined with Reynolds-averaged Navier Stokes is used to predict the sound generated by unsteady viscous ow past a circular cylinder assuming a correlation length of ten cylinder diameters. The twodimensional unsteady ow eld is computed using two NavierStokes codes at a low Mach number over a range of Reynolds numbers from 100 to 5 million. Both laminar o...

Transitional flow, whereby the motion of a fluid changes from laminar to turbulent flow, was successfully identified by Reynolds (1883) almost 130 years ago. According to ASHRAE (2009), for a round pipe, in general, laminar flow exists when the Reynolds number is less than 2 300. Fully turbulent flow exists when the Reynolds number is larger than 10 000 and transitional flow exists for Reynolds...

From observations of swimming of the shell-less pteropod mollusc Clione antarctica we compare swimming velocities achieved by the organism using ciliated surfaces alone with velocities achieved by the same organism using a pair of flapping wings. Flapping dominates locomotion above a swimming Reynolds number Re in the range 5-20. We test the hypothesis that Re ≈ 5-20 marks the onset of “flappin...