The production of turbulence near a smooth wall in a turbulent boundary layer

Kim, H. T.; Kline, S. J.; Reynolds, W. C.

doi:10.1017/s0022112071002490

Cited by 924 publications

(511 citation statements)

References 4 publications

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“…However, a fall in turbulence intensity downstream from the reattachment point leads to sediment deposition and propagation of the defect. The process and supporting evidence have been described in detail by Allen [1982], Gyr and Schmid [1989], and Best [1992] following descriptions of microturbulent structures elaborated in the fluid mechanics literature [e.g., Kline et al, 1967;Kim et al, 1971]. However, Allen [1982] pointed out the gross spatial discordance between the scale of these structures, of order D (grain diameter), and even small transverse bed forms.…”

Section: Introductionmentioning

confidence: 92%

On interfacial instability as a cause of transverse subcritical bed forms

Venditti

Church

Bennett

2006

Water Resources Research

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Recent experimental results suggest there are at least two distinct bed form initiation processes. Bed forms may be generated from local bed defects that are propagated down and across stream by flow separation processes when sediment transport is patchy and sporadic. Alternatively, bed form development may occur over the whole bed at once when sediment transport is general and widespread. Herein, we critically test a simple model for this latter bed form initiation mode that was originally presented by H.‐K. Liu in 1957 but not tested because of the complex nature of the measurements required. The theory is based on the idea that a moving sand bed might be likened to a dense fluid and that a hydrodynamic instability develops at the interface between the sediment transport layer and the near‐bed fluid, leading to the organization of the transport system into laterally extended, discrete bed forms. Our predicted initial bed form lengths are within 10% of the lengths observed in a series of flume experiments, suggesting that transverse waveforms on sand beds sheared by unidirectional currents can be initiated as an interfacial hydrodynamic instability of Kelvin‐Helmholtz type when the current is sufficiently vigorous to produce general sediment movement, that is, to create a sediment transport layer that acts as a pseudofluid with density composed of solid and fluid components.

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Section: Introductionmentioning

confidence: 92%

On interfacial instability as a cause of transverse subcritical bed forms

Venditti

Church

Bennett

2006

Water Resources Research

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“…The reason is that the distribution function (eq 16) is not the appropriate one over a smooth surface. The work of Kim et al (1971) suggested that for smooth surfaces the eddy-contact time has the distribution 0,(1) = (t/tD exp(-t/ts), over an aerodynamically smooth surface that is based on surface-renewal concepts.…”

Section: Aerodynamically Smooth Surfacementioning

confidence: 99%

A theory for the scalar roughness and the scalar transfer coefficients over snow and sea ice

Andreas

1987

Boundary-Layer Meteorol

354

375

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“…The existence of the streaks is, however, well established (see e.g. Kline et al 1967;Kim, Kline & Reynolds 1971;Eckelmann 1974). Note that the difference between horseshoe, hairpin and lambda vortices is largely a function of Reynolds number (Head & Banyopadhyay 1981), with low-Reynolds-number structures having a more horseshoe-like appearance.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional structure of a low-Reynolds-number turbulent boundary layer

2004

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A low-Reynolds-number zero-pressure-gradient incompressible turbulent boundary layer was investigated using a volumetric imaging technique. The Reynolds number based on momentum thickness was 700. The flow was tagged with a passive scalar from two spanwise dye slots to distinguish between fluid motions originating in the inner and outer portions of the boundary layer. The resulting volumetric scalar field was interrogated using a laser sheet scanner developed for this study. Twoand three-dimensional time-dependent visualizations of a 50 volume time series are presented (equivalent to 17δ in length). In the outer portion of the boundary layer, scalar structures were observed to lie along lines in the (x, z)-plane, inclined to the streamwise (x-)direction in the range ±50 • . The ejection of brightly dyed fluid packets from the near-wall region was observed to be spatially organized, and related to the passage of the large-scale scalar structures. IntroductionHere, we present the short-term dynamics of a low-Reynolds-number turbulent boundary layer using three-dimensional visualizations of the scalar field. The interpretations are based on inspection of individual events in a data set comprising a 50 volume time series, equivalent to 17δ in length.It is a well-established observation that a turbulent boundary layer displays structure, in that 'coherent motions' or 'organized motions' are recognized to be an important component of the velocity and pressure fields. Such coherent structures were described by Robinson (1991) as 'a three-dimensional region of the flow over which at least one fundamental flow variable (velocity component, density, temperature, etc.) exhibits significant correlation with itself or with another flow variable over a range of space and/or time that is significantly larger than the smallest local scales of the flow.' Different features appear in the near-wall and outer-layer regions, and we have a broad understanding of their general features. In contrast, the fundamental nature of the motions, their distinguishing characteristics, and the nature of their interactions, are not at all settled. According to an early review by Cantwell (1981), the structure

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The production of turbulence near a smooth wall in a turbulent boundary layer

Cited by 924 publications

References 4 publications

On interfacial instability as a cause of transverse subcritical bed forms

On interfacial instability as a cause of transverse subcritical bed forms

A theory for the scalar roughness and the scalar transfer coefficients over snow and sea ice

Three-dimensional structure of a low-Reynolds-number turbulent boundary layer

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