Self-similarity of time-evolving plane wakes

Moser, Robert D.; Rogers, Michael M.; Ewing, D.

doi:10.1017/s0022112098001426

Cited by 95 publications

(136 citation statements)

References 17 publications

(44 reference statements)

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“…A similar dependence on initial conditions has been observed in wakes and shear layer flows (e.g. Wygnanski, Champagne & Marasli 1986;Ghosal & Rogers 1997;Slessor, Bond & Dimotakis 1998;Moser, Rogers & Ewing 1998;Johansson, George & Gourlay 2003). George (1989) argued that the differences observed in the far field could be due to differences in the large-scale structures generated in the near field that propagate into the fully developed region.…”

Section: Introductionsupporting

confidence: 56%

Two-point similarity in the round jet

Ewing

Frohnapfel

George³

et al. 2007

J. Fluid Mech.

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The governing equations for the two-point velocity correlations in the far field of the axisymmetric jet are examined and it is shown that these equations can have equilibrium similarity solutions for jets with finite Reynolds number that retain a dependence on the growth rate of the jet. The two-point velocity correlation can be written as the product of a scale that depends on the downstream position of the two points and a function that only depends on the similarity variables. Physically, this result implies that the turbulent processes producing and dissipating energy at the different scales of motion, as well as transferring energy between the different scales of motion, are in equilibrium as the flow evolves downstream. A particularly interesting prediction from the analysis is that the two-point similarity solutions depend only on the separation distance between the points in the streamwise similarity coordinate (i.e. υ = ξ − ξ ), that is, the logarithm of the streamwise coordinate itself (i.e. ξ = ln x 1 , where x 1 is measured from a virtual origin). Thus, the measures of the turbulence are homogeneous in the streamwise similarity coordinate.The predictions from the similarity analysis for the streamwise two-point velocity correlation were compared with combined hot-wire and LDA measurements on the centreline of a round jet at a Reynolds number of 33 000, and with two-point velocity correlations computed from PIV measurements in a round jet at a Reynolds number of 2000 performed by Fukushima et al. In both cases, the measured twopoint velocity correlations in the streamwise direction collapsed when they were scaled in the manner predicted by the similarity analysis. The results provide further evidence that the equilibrium similarity hypothesis does describe the development of the flow in fully developed turbulent round jets and that the two-point correlations are statistically homogeneous in the streamwise similarity coordinate.

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Section: Introductionsupporting

confidence: 56%

Two-point similarity in the round jet

Ewing

Frohnapfel

George³

et al. 2007

J. Fluid Mech.

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“…As Lumley* remarked, the dynamics of these interfaces also determine how local regions of intense vortical motions evolve within a general turbulent flow when Re is very large. Recent analysis by Bisset et al (1998) of previously published numerical simulations of wakes (Moser, Rogers & Ewing 1998), has shown that turbulence statistics have a local structure when expressed in terms of the normal distance n I from such interfaces. Even though the Reynolds number of these simulations were not large (Re ∼ 10 2 ) it was found that the conditional profiles of the variables as a function of n I vary sharply near n I = 0 because of the very active small-scale motions at the interface; the vorticity variance ω 2 (n I ) and dissipationε(n I ) were approximately constant for n I /h .…”

Section: New Measurements and Simulationsmentioning

confidence: 99%

Developments in turbulence research: a review based on the 1999 Programme of the Isaac Newton Institute, Cambridge

et al. 2001

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Recent research is making progress in framing more precisely the basic dynamical and statistical questions about turbulence and in answering them. It is helping both to define the likely limits to current methods for modelling industrial and environmental turbulent flows, and to suggest new approaches to overcome these limitations. Our selective review is based on the themes and new results that emerged from more than 300 presentations during the Programme held in 1999 at the Isaac Newton Institute, Cambridge, UK, and on research reported elsewhere. A general conclusion is that, although turbulence is not a universal state of nature, there are certain statistical measures and kinematic features of the small-scale flow field that occur in most turbulent flows, while the large-scale eddy motions have qualitative similarities within particular types of turbulence defined by the mean flow, initial or boundary conditions, and in some cases, the range of Reynolds numbers involved. The forced transition to turbulence of laminar flows caused by strong external disturbances was shown to be highly dependent on their amplitude, location, and the type of flow. Global and elliptical instabilities explain much of the three-dimensional and sudden nature of the transition phenomena. A review of experimental results shows how the structure of turbulence, especially in shear flows, continues to change as the Reynolds number of the turbulence increases well above about 10 4 in ways that current numerical simulations cannot reproduce. Studies of the dynamics of small eddy structures and their mutual interactions indicate that there is a set of characteristic mechanisms in which vortices develop (vortex stretching, roll-up of instability sheets, formation of vortex tubes) and another set in which they break up (through instabilities and selfdestructive interactions). Numerical simulations and theoretical arguments suggest that these often occur sequentially in randomly occurring cycles. The factors that † Now at

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“…In the same study, it was found that, although the wake mean velocity profiles were self-similar for different wake-generating bodies, different spreading rates were reported in each case. These results have been corroborated by [5][6][7][8]. The influence of the state of the boundary layer at the trailing edge of an elongated bluff body has been well documented experimentally [9,10].…”

Section: Introductionmentioning

confidence: 60%

Development of Turbulent Wakes Evolving from Asymmetric Shear Layers

Dghim

Momayez

Ferchichi

et al. 2017

Heat Transfer Engineering

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This paper reports an experimental investigation on the response of a turbulent wake past an elongated flat plate to various upstream flow conditions. Different tripping wires were placed on the upper side of the plate downstream the leading edge resulting in asymmetric shear layers evolving from the trailing edges. Mean flow and turbulent fields of the asymmetric wakes were compared to their symmetrical counterpart. The symmetrical wake was found to attain a self-similar state whereas asymmetric wakes continued to slowly evolve towards an expected asymptotic behaviour at a rate that strongly depends on the imposed initial conditions.

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Self-similarity of time-evolving plane wakes

Cited by 95 publications

References 17 publications

Two-point similarity in the round jet

Two-point similarity in the round jet

Developments in turbulence research: a review based on the 1999 Programme of the Isaac Newton Institute, Cambridge

Development of Turbulent Wakes Evolving from Asymmetric Shear Layers

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