Developing flow in skimming flow regime on embankment stepped spillways

Bung, Daniel B.

doi:10.1080/00221686.2011.584372

Cited by 70 publications

(35 citation statements)

References 15 publications

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“…To illustrate the aerated flow characteristics of skimming flows, Boes and Hager (2003) measured the aerated flow velocity u and the air-concentration ratio C for 30° ≤ θ ≤ 50°. In the nonuniform aerated skimming flow region, Felder and Chanson (2009b) measured u and C for θ =22° and Bung (2011) measured these values for θ =18° and 27°. In the quasi-uniform skimming flow region, Takahashi and Ohtsu (2012) evaluated the energy head of aerated skimming flows for 19° ≤ θ ≤ 55° with the empirical equation for the depth-averaged air-concentration ratio, the velocity profile, and the friction factor, revealing the effect of the channel slope and step height on the specific energy of aerated skimming flows.…”

Section: Introductionmentioning

confidence: 99%

Analysis of nonuniform aerated skimming flows on stepped channels

Takahashi¹,

Ohtsu²

2014

Hydraulic Structures and Society - Engineering Challenges and Extremes

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Section: Introductionmentioning

confidence: 99%

Analysis of nonuniform aerated skimming flows on stepped channels

Takahashi¹,

Ohtsu²

2014

Hydraulic Structures and Society - Engineering Challenges and Extremes

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“…A two dimensional simulation was successful in simulating velocity profiles on stepped spillways. (3) Equation (10) indicates that hydraulic roughness z0 is proportional to shear stress and the hydraulic roughness Froude number F*, defined in terms of the roughness height ks. (4) The turbulent boundary layer is seen at the water surface when the Bauer-defined boundary layer thickness is between 0.72 and 0.79 of the flow depth.…”

Section: Discussionmentioning

confidence: 99%

“…Data of M and F* from the 18 numerical experiments are plotted in Figure 12, and a fitted curve is obtained to describe the relationship between M and F*, (10) Substituting Equation (10) Figure 12. The relationship between F* and M.…”

Section: Estimation Of Velocity Profile Parametersmentioning

confidence: 99%

“…At the step edges, the vertical velocity distribution in the turbulent boundary layer can be approximated by a power law [8][9][10][11], and data obtained in bed-roughened flows show that there is a region above the roughness layer where the smooth boundary upstream of the steps still adequately describes the vertical velocity distribution [12][13][14]. This transition boundary layer will be used to investigate and characterize the roughness parameters and the development of turbulent boundary layer.…”

Section: Introductionmentioning

confidence: 99%

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Application of Displacement Height and Surface Roughness Length to Determination Boundary Layer Development Length over Stepped Spillway

Cheng

Gulliver

Zhu

2014

Water

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Abstract:One of the most uncertain parameters in stepped spillway design is the length (from the crest) of boundary layer development. The normal velocity profiles responding to the steps as bed roughness are investigated in the developing non-aerated flow region. A detailed analysis of the logarithmic vertical velocity profiles on stepped spillways is conducted through experimental data to verify the computational code and numerical experiments to expand the data available. To determine development length, the hydraulic roughness and displacement thickness, along with the shear velocity, are needed. This includes determining displacement height d and surface roughness length z0 and the relationship of d and z0 to the step geometry. The results show that the hydraulic roughness height ks is the primary factor on which d and z0 depend. In different step height, step width, discharge and intake Froude number, the relations d/ks = 0.22-0.27, z0/ks = 0.06-0.1 and d/z0 = 2.2-4 result in a good estimate. Using the computational code and numerical experiments, air inception will occur over stepped spillway flow as long as the Bauer-defined boundary layer thickness is between 0.72 and 0.79. OPEN ACCESSWater 2014, 6 3889 Keywords: displacement height; surface roughness length; stepped spillway; boundary layer development; numerical simulations; logarithmic law; inception of air entrainment

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“…Severe erosions at the downstream channel may harm the stability of the hydraulic structures as documented by Dodaro et al [43,44]. More practical issues on the stepped spillway design and energy dissipation have been thoroughly studied in the benchmark of [45][46][47]. Therefore, a thorough understanding of the energy dissipation features can help to better evaluate the design of stepped spillways and other energy dissipaters such as the tailing basin.…”

Section: Analysis Of Energy Dissipation Efficiency Of Spillway With Dmentioning

confidence: 99%

SPHysics Simulation of Experimental Spillway Hydraulics

Ren

Wang

et al. 2017

Water

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Abstract:In this paper, we use the parallel open source code parallelSPHysics based on the weakly compressible Smoothed Particle Hydrodynamics (WCSPH) approach to study a spillway flow over stepped stairs. SPH is a robust mesh-free particle modelling technique and has great potential in treating the free surfaces in spillway hydraulics. A laboratory experiment is carried out for the different flow discharges and spillway step geometries. The physical model is constructed from a prototype reservoir dam in the practical field. During the experiment, flow discharge over the weir crest, free surface, velocity and pressure profiles along the spillway are measured. In the present SPH study, a straightforward push-paddle model is used to generate the steady inflow discharge in front of the weir. The parallelSPHysics model is first validated by a documented benchmark case of skimming flow over a stepped spillway. Subsequently, it is used to reproduce a laboratory experiment based on a prototype hydraulic dam project located in Qinghai Province, China. The detailed comparisons are made on the pressure profiles on the steps between the SPH results and experimental data. The energy dissipation features of the flows under different flow conditions are also discussed. It is shown that the pressure on the horizontal face of the steps demonstrates an S-shape, while on the vertical face it is negative on the upper part and positive on the lower part. The energy dissipation efficiency of the spillway could reach nearly 80%.

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Developing flow in skimming flow regime on embankment stepped spillways

Cited by 70 publications

References 15 publications

Analysis of nonuniform aerated skimming flows on stepped channels

Analysis of nonuniform aerated skimming flows on stepped channels

Application of Displacement Height and Surface Roughness Length to Determination Boundary Layer Development Length over Stepped Spillway

SPHysics Simulation of Experimental Spillway Hydraulics

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