Flow Velocity Profiles in Gravel‐Bed Rivers

Ferro, Vito; Baiamonte, Giorgio

doi:10.1061/(asce)0733-9429(1994)120:1(60)

Cited by 91 publications

(72 citation statements)

References 21 publications

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“…It is difficult to establish a general tendency in the observed deviations, because they occur in both upstream and downstream directions by a relative increase or decrease of the flow velocity. In decelerating flows, the time-averaged velocity profile in gravel-bed rivers may acquire a so-called D-shape ( [16]). …”

Section: Time-averaged Velocity Profilesmentioning

confidence: 99%

“…It can be seen in Figs. 5, 6 and 8 that some velocity profiles have strong deviations from the logarithmic shape in the outer layer, most likely due to permanent 3D structures in the flow [16,5,48,20]). Franca [20] showed the occurrence of organized time-averaged secondary motion in these flows which is confined to the outer layer (z > % 0.80h).…”

Section: Parameterization Of the Logarithmic Layer Of The Double-avermentioning

confidence: 99%

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Parameterization of the logarithmic layer of double-averaged streamwise velocity profiles in gravel-bed river flows

Franca

Ferreira²,

Lemmin

2008

Advances in Water Resources

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a b s t r a c tThe logarithmic layer of double-averaged (in time and space) streamwise velocity profiles obtained from field measurements made in the Swiss rivers, Venoge and Chamberonne is parameterized and discussed. Velocity measurements were made using a 3D Acoustic Doppler Velocity Profiler. Both riverbeds are hydraulically rough, composed of coarse gravel, with relative submergences (h/D 50 ) of 5.25 and 5.96, respectively. From the observations, the flow may be divided into three different layers: a roughness layer near the bed, an equivalent logarithmic layer and a surface or outer layer. It was found that a logarithmic law can describe the double-averaged profiles in the layer 0.30 < z/h < 0.75. The parameterization of the logarithmic law is discussed. Special emphasis is given to the geometric parameters roughness and zerodisplacement heights and to the equivalent von Karman constant.

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Section: Time-averaged Velocity Profilesmentioning

confidence: 99%

Section: Parameterization Of the Logarithmic Layer Of The Double-avermentioning

confidence: 99%

Parameterization of the logarithmic layer of double-averaged streamwise velocity profiles in gravel-bed river flows

Franca

Ferreira²,

Lemmin

2008

Advances in Water Resources

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“…In the outer region the velocity distribution can be described by the velocity defect law [Prandtl, 1925;Hinze, 1975] obtained from (1) by assuming that the maximum velocity occurs at the free surface [Ferro and Baiamonte, 1994]. In other words, both in the fully turbulent part of the inner region and in the outer region a velocity profile having a logarithmic shape can be assumed [Kirkgoz and Ardiqhoglu, 1997].…”

mentioning

confidence: 99%

“…(2) The bed particles should have no uniform size distribution to allow the development of the lower zone flow. Ferro and Baiamonte [1994] showed that the Dean-Finley profile can be used for establishing the flow velocity profile in a gravel bed channel for a condition of both large-and smallscale roughness: , u-•=b0+b•logz+b2z2(1-z) +b3z2(3-2z), (4) in which b0, b•, b2, and b 3 are numerical constants to be estimated by using velocity measurements. The two cubic components of (4) allow one to obtain a profile with a maximum below the water surface and S-shaped.…”

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confidence: 99%

Incomplete self‐similarity and flow velocity in gravel bed channels

Ferro¹,

Pecoraro²

2000

Water Resources Research

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Abstract. Velocity measurements, previously carried out using both a miniature current flowmeter and an acoustic Doppler velocimeter, are used to verify the applicability of the incomplete self-similarity theory to deduce the velocity profile in a gravel bed channel. Then, for the velocity profiles having the maximum value below the free surface and for the S-shaped profiles, the power velocity distribution is corrected using a new divergence function. For each value of the depth sediment ratio the nondimensional friction factor parameter is calculated by integration of the measured velocity distributions in the different verticals of the cross section. Finally, a semilogarithmic flow resistance equation is empirically deduced.

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“…For the condition of large-scale roughness, if d 50 is comparable to D (say D/d 50 < 2.0), the flow can be assumed to be a mixing layer flow [2]. The flow velocity profile may be S-shaped (Figure 1(b)) with near-surface velocities much larger than near-bed velocities [3]. The criterion differentiating the small-scale and large-scale roughness is not clear-cut, and depends on the shape, concentration and arrangement of the roughness elements.…”

Section: Introductionmentioning

confidence: 99%

Modeling Flows over Gravel Beds by a Body Force Method

Zeng¹,

Li²,

Li³

et al. 2011

AIP Conference Proceedings

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A new boundary condition for the three-dimensional Navier-Stokes equation and the vanishing viscosity limit J. Math. Phys. 53, 115617 (2012) Vortex stretching and criticality for the three-dimensional Navier-Stokes equations J. Math. Phys. 53, 115613 (2012) Flow past a normal flat plate undergoing inline oscillations Phys. Fluids 24, 093603 (2012) Conditional regularity of solutions of the three-dimensional Navier-Stokes equations and implications for intermittency J. Math. Phys. 53, 115608 (2012) Additional information on AIP Conf. Proc. Abstract A Reynolds-averaged Navier-stokes equations (RANS) model using the body force method (BFM) has been developed to simulate open-channel flows over gravel beds. The momentum equation is modified by introducing the form drag as an extra body force term to represent the gravel-bed resistance. By applying the body force within the roughness layer of the flow over small-scale roughness, it is found that the body force coefficient f rk varies inversely with the roughness length scale k s . The method is robust, not sensitive to mesh resolution and is easily extended to deal with large scale roughness.

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Flow Velocity Profiles in Gravel‐Bed Rivers

Cited by 91 publications

References 21 publications

Parameterization of the logarithmic layer of double-averaged streamwise velocity profiles in gravel-bed river flows

Parameterization of the logarithmic layer of double-averaged streamwise velocity profiles in gravel-bed river flows

Incomplete self‐similarity and flow velocity in gravel bed channels

Modeling Flows over Gravel Beds by a Body Force Method

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