Mean Streamwise Spacing of Organized Structures in Transitional and Developed Bounded Turbulent Flows

Wallace, J. M.; Fleischmann, Shirley

doi:10.2514/3.48515

Cited by 16 publications

(7 citation statements)

References 23 publications

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“…Laufer & Narayanan (1971) proposed outer scaling for the mean time, and they found a value of U ∞ T /δ = 5 that was substantially independent of the Reynolds number (U ∞ is the free-stream velocity). The review by Bandyopadhyay (1982) concludes that 2.5 < U ∞ T /δ < 10, while the review by Fleischmann & Wallace (1984) used scaling with the local mean velocity to reduce the spread to 1.5 < U ∞ T /δ < 3.5, very close to the mean length of a turbulent bulge. Also, see the discussion of LSMs in Falco (1991).…”

Section: Introductionmentioning

confidence: 99%

“…Also, see the discussion of LSMs in Falco (1991). Fleischmann & Wallace (1984) also associated the large-scale motions in bounded flows such as in pipes and channels with those in the turbulent boundary layer. Using proper orthogonal decomposition (POD) on a domain 2.4h long in channel flow to evaluate the energy distribution associated with two-dimensional patterns in the streamwise-wall-normal plane, Liu, Adrian & Hanratty (2001) found over half of the layer-averaged kinetic energy residing in the lowest-order modes.…”

Section: Introductionmentioning

confidence: 99%

“…KA99 suggested that the structures with wavelengths of approximately 2R-3R are associated with the organization and streamwise alignment of hairpin vortices into hairpin packets that ultimately grow to become bulges, since the mean length of the bulges is known to be of this size. The turbulent bulges found by Kovasznay et al (1970) are a phenomenon of the boundary layer, but evidence found since shows that bulge-like structures also occur in pipes and channels (Fleischmann & Wallace 1984). For purposes of discussion of the wake region we decided earlier to use k x R = 2, corresponding to λ = πR, to delimit low wavenumbers (very-large-scale motions) 10 -1 10 0 10 1 10 2 10 -4 10 -3…”

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confidence: 99%

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Large-scale and very-large-scale motions in turbulent pipe flow

2006

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In the outer region of fully developed turbulent pipe flow very large-scale motions reach wavelengths more than 8$R$–16$R$ long (where $R$ is the pipe radius), and large-scale motions with wavelengths of $2R$–$3R$ occur throughout the layer. The very-large-scale motions are energetic, typically containing half of the turbulent kinetic energy of the streamwise component, and they are unexpectedly active, typically containing more than half of the Reynolds shear stress. The spectra of the $y$-derivatives of the Reynolds shear stress show that the very-large-scale motions contribute about the same amount to the net Reynolds shear force, d$\overline{-u'v'}/{\rm d}y$, as the combination of all smaller motions, including the large-scale motions and the main turbulent motions. The main turbulent motions, defined as the motions small enough to be in a statistical equilibrium (and hence smaller than the large-scale motions) contribute relatively little to the Reynolds shear stress, but they constitute over half of the net Reynolds shear force.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Large-scale and very-large-scale motions in turbulent pipe flow

2006

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“…e.g. Bandyopadhyay (1983), Fleischmann & Wallace (1984) and Johansson, Her & Haritonidis (1987) have commented on the similarity between characteristics of vortex loops in a spot and those in a fully developed boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Substructures in a turbulent spot

1988

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Substructures within a turbulent spot which develops in a slightly heated laminar boundary layer have been identified using arrays of cold wires aligned in either a streamwise direction or in a direction normal to the wall. At any given streamwise distance from the spot origin, histograms of the number of detected substructures exhibit a peak, defining the most probable spot or the spot with the most likely number of substructures. The number of substructures in the most probable spot increases with streamwise distance but all substructures are convected at approximately the same velocity for any given distance from the wall. This velocity is approximately equal to that of the leading edge of the spot and increases slightly with distance from the wall. The increase in the number of substructures accounts for the streamwise growth of the spot. A simple relation is derived for determining the number of substructures at a particular streamwise station and a geometrical construction is proposed for identifying the origin of a new substructure. There is sufficient evidence for suggesting that the new substructures are formed near the trailing edge of the spot. The convection velocity, inclination and lengthscales of the substructures compare favourably with the corresponding characteristics of hairpin vortices.

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“…Rao, Narasimha & Badri Narayanan (1971) and Laufer & Badri Narayanan (1971) reported that the mean period between the successive events became independent of the Reynolds number when non-dimensionalized by the outer-flow timescale 6 / U , ( U , is free-stream velocity, I S the boundary-layer thickness). This stimulated speculation about the relation between the events in the wall region and the large-scale structure in the outer layer (Laufer & Badri Narayanan 1971 ;Brown & Thomas 1977;Falco 1977;Fleischmann & Wallace 1984). On the other hand, some reports insisted that the period of events should scale with the viscous timescale V / U *~.…”

Section: Introductionmentioning

confidence: 99%

The effect of spatial restriction on the inner-layer structure of wall turbulence

Maruyama¹,

Tanaka²

1987

J. Fluid Mech.

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Hot-film-anemometer measurements were carried out in a shear flow between a flat plate and a moving plate fitted with an array of tall fences. The effect of spatial restriction by the fences on the inner-layer structure of the boundary layer developing on the flat-plate side was investigated. It was revealed that the inner-layer structure was maintained even when the tips of the fences were passing at a distance y+ = 45 from the flat plate; the flow did not become laminar-like until the tips reached y+ = 25. These results suggested the physical view that the inner layer of wall turbulence has a tough, self-sustaining structure, which is uniquely determined under a given mean wall shear stress and is hardly influenced by outer-layer disturbances provided that its own spatial extent of about 45 ν/u* from the wall is maintained.

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Mean Streamwise Spacing of Organized Structures in Transitional and Developed Bounded Turbulent Flows

Cited by 16 publications

References 23 publications

Large-scale and very-large-scale motions in turbulent pipe flow

Large-scale and very-large-scale motions in turbulent pipe flow

Substructures in a turbulent spot

The effect of spatial restriction on the inner-layer structure of wall turbulence

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