Uniform flow in a smooth open channel

Cardoso, António H.; Graf, Wolfgang; Gust, G.

doi:10.1080/00221688909499113

Cited by 153 publications

(107 citation statements)

References 8 publications

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“…(2), relatively consistent values have been found in different literature studies. A range of j = 0.40-0.42 was proposed for the flows over smooth bed investigated by Coles [6] and Cardoso et al [4]; while, similar value (j = 0.40) was also suggested for the rough bed flow by Song et al [30]. More recently, Auel et al [2] summarised from various smooth and rough bed flow studies that j = 0.385-0.435, universally.…”

Section: Uniform Flow Results and Analysismentioning

confidence: 92%

“…In those studies, some have suggested higher values, namely Nezu and Rodi [20]-G = 0.20; while others proposed lower values, namely Kirkgoz [11]-G = 0.10, Steffer et al [31]-G = 0.08-0.15, and Cardoso et al [4]-G = 0.079 ± 0.093. When compared to rough bed flow studies, i.e.…”

Section: Uniform Flow Results and Analysismentioning

confidence: 99%

“…More recently, Auel et al [2] summarised from various smooth and rough bed flow studies that j = 0.385-0.435, universally. For the log-law integration constant B r of smooth bed uniform flows, it was proposed as B r = 4.9 in Mellor and Gibson [15], and Anwar and Atkins [1]; and B r = 5.1 in Coles [6], and Cardoso et al [4]. In comparison to different rough bed flow studies (i.e.…”

Section: Uniform Flow Results and Analysismentioning

confidence: 99%

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Dominant features in three-dimensional turbulence structure: comparison of non-uniform accelerating and decelerating flows

Tait

Guo

et al. 2017

Environ Fluid Mech

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The results are presented from an experimental study to investigate three-dimensional turbulence structure profiles, including turbulence intensity and Reynolds stress, of different non-uniform open channel flows over smooth bed in subcritical flow regime. In the analysis, the uniform flow profiles have been used to compare with those of the nonuniform flows to investigate their time-averaged spatial flow turbulence structure characteristics. The measured non-uniform velocity profiles are used to verify the von Karman constant j and to estimate sets of log-law integration constant B r and wake parameter G, where their findings are also compared with values from previous studies. From j, B r and G findings, it has been found that the log-wake law can sufficiently represent the nonuniform flow in its non-modified form, and all j, B r and G follow universal rules for different bed roughness conditions. The non-uniform flow experiments also show that both the turbulence intensity and Reynolds stress are governed well by exponential pressure gradient parameter b equations. Their exponential constants are described by quadratic functions in the investigated b range. Through this experimental study, it has been observed that the decelerating flow shows higher empirical constants, in both the turbulence intensity and Reynolds stress compared to the accelerating flow. The decelerating flow also has stronger dominance to determine the flow non-uniformity, because it presents higher Reynolds stress profile than uniform flow, whereas the accelerating flow does not.

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Section: Uniform Flow Results and Analysismentioning

confidence: 92%

Section: Uniform Flow Results and Analysismentioning

confidence: 99%

Section: Uniform Flow Results and Analysismentioning

confidence: 99%

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Dominant features in three-dimensional turbulence structure: comparison of non-uniform accelerating and decelerating flows

Tait

Guo

et al. 2017

Environ Fluid Mech

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“…For such flows, velocity profiles can be approximated by the conventional log law or the log-wake law (Steffler et al 1985;Nezu and Rodi 1986;Kirkgoz 1989;Cardoso et al 1989;Kironoto and Graf 1994;Muste and Patel 1997).…”

Section: Introductionmentioning

confidence: 99%

Application of Modified Log-Wake Law in Open-Channels

Guo¹,

Juliën

2006

World Environmental and Water Resource Congress 2006

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The modified log-wake law, which was developed for turbulent boundary layers and pipe flows, is extended to turbulent flows in open-channels. Turbulent velocity profiles in open-channels can be approximated with three components: (1) the law of the wall that results from the constant bed shear stress; (2) the law of the wake that reflects the effects of gravity, secondary currents and bed roughness; and (3) the cubic correction near the maximum velocity. A procedure to determine the four model parameters from velocity measurements while keeping κ = 0.41 is presented. The modified log-wake law compares very well with experimental data from Coleman, Lyn, Kironoto and Graf and Sarma et al. It also replicates the measured velocity profiles of the Mississippi River. In particular, it can well fit the velocity dip phenomenon in openchannels where the conventional log-wake law fails.

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“…In previous studies, relatively consistent values have been proposed for the von Karman constant κ. A range of 0.40-0.42 for κ was suggested for the smooth bed flows reported in Coles [9] and Cardoso et al [19]; whereas, κ ≈ 0.40 was proposed for the rough bed flow investigated by Song et al [20]. In recent investigation, a universal κ ≈ 0.41 ± 5% was proposed by Auel et al [21] for both smooth and rough bed flows after reviewing works from different studies.…”

Section: Velocity Profilementioning

confidence: 96%

Velocity Distribution and 3D Turbulence Characteristic Analysis for Flow over Water-Worked Rough Bed

Wei

Huang

2017

Water

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Abstract:To reproduce the natural flow topography in a laboratory environment, it is crucial to recapture its bed condition in order to ensure the accurate representation. Water-worked bed represents a state-of-the-art experimentally formed bed to imitate the natural-formed channel in most rivers or natural streams. Recently, this technique has been intensively studied through experimental and computational approaches; however, its actual influence towards the near-bed flow as compared to experimentally prepared rough bed in well-packed bedform order are still yet to be investigated deeply. This experimental study systematically investigated and compared the differences in velocity distribution and three-dimensional (3D) turbulence characteristics, including turbulence intensities and Reynolds stresses, between uniform smooth bed, laboratory-prepared rough bed and water-worked bed open channel flows. The flow comparisons were concentrated at near-bed region where clear flow behaviour change can be observed. Through these comparisons, the study inspected the characteristics of water-worked bedform thoroughly, in order to inform future experimental research that tries to reproduce natural stream behaviours.

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Uniform flow in a smooth open channel

Cited by 153 publications

References 8 publications

Dominant features in three-dimensional turbulence structure: comparison of non-uniform accelerating and decelerating flows

Dominant features in three-dimensional turbulence structure: comparison of non-uniform accelerating and decelerating flows

Application of Modified Log-Wake Law in Open-Channels

Velocity Distribution and 3D Turbulence Characteristic Analysis for Flow over Water-Worked Rough Bed

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