Skimming Flow in the Nonaerated Region of Stepped Spillways over Embankment Dams

Meireles, Inês; Matos, Jorge

doi:10.1061/(asce)hy.1943-7900.0000047

Cited by 73 publications

(46 citation statements)

References 8 publications

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“…In the step cavities, recirculating zones become well defined (not shown herein). steep slopes, either on the non-aerated [64,66] or on the gradually varied or quasi uniform aerated flow regions [4,9]. In turn, Felder and Chanson [37] found a value of N = 10 for the velocity profile in the aerated region.…”

Section: Verification Of the Volumetric Flow Rate (Discharge) Water mentioning

confidence: 99%

“…Empirical models have been developed for predicting the main air-water flow properties along the chute by Hager and Boes [45], Matos [57], Chanson [25], Boes and Hager [9,10], Meireles [65], Renna [71] and Ohtsu et al [67]. In spite of this considerable number of studies, and to the best of our knowledge, only Amador [2], Amador et al [3], Meireles et al [65], Gonzalez and Chanson [43], Carvalho and Amador [23] and Meireles and Matos [64] have focused on the flow properties of the non-aerated flow region of stepped spillways.…”

Section: Introductionmentioning

confidence: 99%

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Laboratory measurements and multi-block numerical simulations of the mean flow and turbulence in the non-aerated skimming flow region of steep stepped spillways

2010

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We present and discuss the results of a comprehensive study addressing the non-aerated region of the skimming flow in steep stepped spillways. Although flows in stepped spillways are usually characterized by high air concentrations concomitant with high rates of energy dissipation, the non-aerated region becomes important in small dams and/or spillways with high specific discharges. A relatively large physical model of such spillway was used to acquire data on flow velocities and water levels and, then, well-resolved numerical simulations were performed with a commercial code to reproduce those experimental conditions. The numerical runs benefited from the ability of using multi-block grids in a Cartesian coordinate system, from capturing the free surface with the TruVOF method embedded in the code, and from the use of two turbulence models: the k−ε and the RNG k−ε models. Numerical results are in good agreement with the experimental data corresponding to three volumetric flow rates in terms of the time-averaged velocities measured at diverse steps in the spillway, and they are in very satisfactory agreement for water levels along the spillway. In addition, the numerical results provide information on the turbulence statistics of the flow. This work also discusses important aspects of the flow, such as the values of the exponents of the power-law velocity profiles, and the characteristics of the development of the boundary layer in the spillway.

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Section: Verification Of the Volumetric Flow Rate (Discharge) Water mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Laboratory measurements and multi-block numerical simulations of the mean flow and turbulence in the non-aerated skimming flow region of steep stepped spillways

2010

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“…The feasibility of using such a push-paddle approach has been demonstrated in a validation work carried out for the weir flow in [40]. Here we use this inflow technique to reproduce the numerical simulation of [31] and experimental study [41] by using the open source code parallelSPHysics.…”

Section: Model Validations Through Benchmark Spillway Flowmentioning

confidence: 99%

“…Meireles and Matos [41] conducted experimental studies on a stepped spillway that was 0.5 m high with 1V:2H slope. The base weir is broad-crested with a length of 0.5 m. It has 10 steps, each with 0.05 m in height and 0.1 m in width.…”

Section: Model Validations Through Benchmark Spillway Flowmentioning

confidence: 99%

“…In the current parallelSPHysics simulations, the test condition of hc = 0.07935 m, 0.0716 m and 0.0635 m as shown in Table 1 in [31] is used. Based on the simulation results, Table 1 presents the experimental [31,41] and parallelSPHysics values of the discharge per unit width (q) for the different critical flow depths (hc) over the weir crest. It seems a good agreement has been reached.…”

Section: Model Validations Through Benchmark Spillway Flowmentioning

confidence: 99%

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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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Aeration and air–water mass transfer on stepped chutes with embankment dam slopes

Felder

Chanson

2014

Environ Fluid Mech

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Stepped spillway flows are characterised by significant free-surface aeration downstream of the inception point of air entrainment. The stepped design is advantageous for applications which require large energy dissipation and strong flow aeration. While the energy dissipation rate for embankment stepped spillways was studied previously, the optimum design for aeration and air-water mass transfer is not known. Herein new air-water flow experiments were conducted on several stepped spillways with embankment dam slopes using with phasedetection intrusive probes. The present data were compared with previous studies in terms of energy dissipation, flow aeration and air-water mass transfer. The air-water mass transfer was calculated based upon air-water flow measurements in terms of dissolved oxygen. The re-oxygenation rates were compared with previous studies comprising both conductivity and direct dissolved oxygen measurements. The comparison highlighted a monotonic increase of aeration efficiency with energy dissipation rate. All data were in good agreement independent of channel slopes, stepped configuration and sensor size. The data confirmed the effects of strong air-water interactions within the bulk of the flow for both energy dissipation and re-oxygenation performances.

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Skimming Flow in the Nonaerated Region of Stepped Spillways over Embankment Dams

Cited by 73 publications

References 8 publications

Laboratory measurements and multi-block numerical simulations of the mean flow and turbulence in the non-aerated skimming flow region of steep stepped spillways

Laboratory measurements and multi-block numerical simulations of the mean flow and turbulence in the non-aerated skimming flow region of steep stepped spillways

SPHysics Simulation of Experimental Spillway Hydraulics

Aeration and air–water mass transfer on stepped chutes with embankment dam slopes

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