The structure of the viscous sublayer and the adjacent wall region in a turbulent channel flow

Eckelmann, Helmut

doi:10.1017/s0022112074001479

Cited by 356 publications

(158 citation statements)

References 11 publications

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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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Section: Introductionmentioning

confidence: 99%

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

2004

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“…One may try to do this by increasing the viscous length scale, /uy either by reducing,u, by lowering the free stream speed or by increasing, V, as Eckelmann (1974) has done in his oil channel measurements. Both these methods reduce the Reynolds number of the flow and make the wall region very thick compared to the boundary layer thickness.…”

Section: W W Willmarthmentioning

confidence: 99%

“…Eckelmann (1970Eckelmann ( , 1974, Kreplin, Eckelmann and Wallace (1974), Kreplin (1976) and ri're recently Blackwelder and Eckelmann (1977a) made correlation measurements in conjunction with an investigation of the structure of the near-wall region. The thick viscous sublayer of the oil channel allowel measurements very close to the wall.…”

Section: Space-time Correlationmentioning

confidence: 99%

Workshop on Coherent Structure of Turbulent Boundary Layers.

Abbott¹,

Smith²

1978

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“…Consider first a turbulent boundary layer flowing over an erodible boundary. Several recent studies 1967;Corino and Brodkey, 1969;Grass, 1971;Eckelmann, 1974) have shown that flow in a turbulent boundary layer near rough and smooth boundaries is characterized by ej'ection of low-momentum fluid parcels away from the boundary and inrush of high-momentum fluid parcels toward the boundary, This phenomenon has been termed bursting; the threedimensional picture is one of eddies bursting from the bed, being entrained in the flow near the bed, and stretching in a downstream sense (Kim et al, 1971). It has further been suggested (Grass, 1971) that this process of momentum exchange is primarily responsible for turbulence production near the boundary,…”

Section: Conceptual Model For Erosion Of Fine-grained Sedimentsmentioning

confidence: 99%

Flow and sediment properties influencing erosion of fine-grained marine sediments : sea floor and laboratory experiments

Young¹

1975

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Erosion processes involving fine-grained marine sediments were studied by using an in situ flume to erode undisturbed bottom sediments on the sea floor in Buzzards Bay, a shallow marine embayment off the Massachusetts coast. The muddy sea floor in that area is characterized by a deposit-feeding infauna that reworks the sediments.Observations made with the in situ flume suggest that erosion resistance of compacted bottom sediments is up to twice as great as the erosion resistance of biogenically reworked sediments. Estimates of erosional bed shear stress from the in situ flume experiments are similar to estimates made during this study of bed shear stress developed in near-bottom tidal currents. It is inferred that erosion by the in situ flume produces reasonable estimates of bed shear stress necessary to erode undisturbed bottom sediments on the sea floor.Buzzards Bay muds were redeposited in a laboratory flume and eroded after various periods of reworking by the deposit-feeding organisms contained in them, Other Buzzards Bay mud samples were treated to remove organic matter, and the erosion resistance of flat beds of these sediments was also investigated in a laboratory flume.The surface of a biogenically reworked bed after two months was covered with mounds, burrows, trails, and aggregates composed of sediments and organic material. This bed was similar in appearance to many of the beds eroded by the in situ flume. The two month bed eroded at an erosional shear stress similar to the erosional shear stress necessary to erode the in situ Buzzards Bay muds (0.8 dynes/cm 2 ). Beds biogeiically reworked for shorter periods had high values or erosional shear stress, up to twice that of the two month bed.The bed shear stress necessary to erode flat beds of Buzzards Bay sediments increased as the concentration of organic matter in the sediments increased. Depositfeeders were absent in these beds, and the mode of deposition was kept uniform, so the increase of erosion resistance with increase in organic content is considered a reliable indication of sediment behavior, and not an artifact of experimental conditions. During the in situ experiments, lee drifts were created behind resistant roughness elements on the sea floor. A brief study of lee drift formation in the laboratory suggests that the formation of lee drifts from fine-grained sediments can be predicted to take place when the body Reynolds number of the resistant roughness elements is below a critical value. ACKNOWLEDGMENTS

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The structure of the viscous sublayer and the adjacent wall region in a turbulent channel flow

Cited by 356 publications

References 11 publications

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

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

Workshop on Coherent Structure of Turbulent Boundary Layers.

Flow and sediment properties influencing erosion of fine-grained marine sediments : sea floor and laboratory experiments

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