Volume of Fluid Model for Turbulence Numerical Simulation of Stepped Spillway Overflow

Chen, Qun; Dai, Guangqing; Hao-wu, Liu

doi:10.1061/(asce)0733-9429(2002)128:7(683)

Cited by 138 publications

(92 citation statements)

References 8 publications

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Section: Introductionmentioning

confidence: 99%

“…A small number of simulations of the skimming flow over stepped spillways have been communicated very recently [5,23,[29][30][31]79], describing both the aerated and non-aerated flow regions. A detailed analysis of the above contributions for stepped spillways is presented in Table 1, revealing the following features/issues: (i) The comparisons between numerical and experimental results in those papers have been mostly of qualitative nature; Issues with the measurements in the aerated region [86] Cheng et al [30,31] (ii) whereas Chen et al [29] (see also Yasuda et al [86]), Cheng et al [30,31] and Arantes [5] solved the flows of water and air altogether (which was defined as Partial Volume-of-Fluid (VoF) method in Bombardelli et al [16]), Tabbara et al [79] employed a numerical strategy based on re-meshing each time step. In turn, Carvalho and Amador [23] used a purported VoF method, but they did not report comparisons of numerical results with data of the location of the free surface; (iii) some of the simulations have been developed using unstructured grids with good resolution near the walls but with a lower resolution near the free surface; (iv) only the papers by Cheng et al [30,31] and Carvalho and Amador [23] include discussions on the distribution of turbulence statistics in the steps through contours of the turbulent kinetic energy (TKE) obtained numerically; (v) experimental data obtained in some papers to validate the numerical simulations corresponded to relatively small facilities with potential significant scale effects; (vi) to the best of our knowledge, very few numerical analyses of the non-aerated flow region which present and discuss comprehensive comparisons of computational results with data have been published in reputed peer-reviewed literature.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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: Introductionmentioning

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 negative pressure plotted in Fig. 11 were also predicted by Chen et al (2002) for a WES structure with the transition steps. Fig.…”

Section: Pressure Diagram Distributionmentioning

confidence: 55%

Analysis of Two Phase Flows on Stepped Spillways

Lobosco¹,

Schulz²,

Simões³

2011

Hydrodynamics - Optimizing Methods and Tools

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cavitation damages (Gomes, 2006;Olinger, 2001). The obtained results presented in this chapter are still approximate, but already show that the problem is treatable using numerical tools. The main problems, as shown in this chapter, are related to the behavior of the free surface. This study considers the skimmimg flow regime, which generally occurs for large specific water discharges (Chanson, 2000). It is expected that the bed profile of the inlet structure affects the position of the inception point of the aeration (Boes & Hager, 2003a;Chanson, 2001). This study presents results of computational analyses for two inlet conditions of a stepped chute with an ogee crest. The aeration of the flows was investigated for an entry profile containing 1) steps with the same size, and 2)"transition steps" (steps with sizes increasing between the smooth bed and the stepped bed). In the last few decades, the computational fluid dynamics, CFD, has imposed itself as one of the best tools for the prediction of flow fields with accuracy and detail (Versteeg & Malalasekera, 1995). But even considering its success, complex flows still need many efforts to be completely understood. The description of the physical processes of a two phase flow involves a broad variety of computational methodologies to predict the quantities of the constituent components and the behavior of the interface. In the present study, the numerical procedures for the stepped channel flow simulations were conducted using the open softwares Salome and OpenFoam® (Open Source Field Operation and Manipulation), for mesh generation and CFD, respectively. In a general way, it may be commented that the implementation of CFD modeling is still limited, due, in part, to the relatively high costs of the commercial softwares. OpenFoam® is an open CFD software that helps to fill this gap. For the purposes of this chapter, the particularly relevant characteristic of the mentioned software is its ability to simulate flows interacting with hydraulic structures. The skimming flows along stepped chutes are inherently turbulent (Lima, 2003, Chamani, 2000, and their "turbulent characteristics" were investigated here using the "k-ε" model of turbulence, and adequate wall functions for the wall boundaries. The VOF method (Volume Of Fluid), was used for the interface-capturing procedures in the two-fluid model. Further, the PISO method (Pressure-Implicit with Splitting of Operators) was used as the pressurevelocity coupling scheme. In the calculations performed for this chapter, the rasInterFoam solver was chosen because, traditionally, the flow along spillways is considered incompressible (its velocity is much lower than the speed of the sound in water). The main purposes of this chapter were to show the implementation of the mentioned open softwares for the problem of aerated flows over stepped chutes, and to compare some calculated hydrodynamics characteristics with the literature, like the pressure distribution on the steps. The literature addresses the position of the incept...

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“…Among the k-style models (standard, RNG, and Realizable) and the kturbulent models, the k-standard is selected to be considered in this study as the first turbulent model attempt, due to its simplicity and reasonable cost. Furthermore, it has been previously used to successfully simulate flow over stepped spillways [9]. This turbulent model solves "k" and " "equations as additional PDEs to find turbulent viscosity.…”

Section: Turbulence Modelingmentioning

confidence: 99%

“…Chamani and Rajaratnam also Chanson Performed experiments on the Skimming Flow regime and devolved experimental formulas to determine the energy loss rate in this regime [5] [6]. Some efforts has been made to use numerical simulation and machine learning in engineering [7] [8].Chen et al used finite volume method and utilized the k-ε turbulent model to determine flow turbulence in stepped spillways [9]. Tabbara et al simulated the flow over stepped spillway by the finite element method using ADINA software with the k-ε standard turbulence model [10].…”

Section: Introductionmentioning

confidence: 99%

Energy Loss Estimation and Flow Simulation in the skimming flow Regime of Stepped Spillways with Inclined Steps and End Sill: A Numerical Model

Hamedi¹,

Ketabdar²

2016

IJSEA

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Abstract:Energy dissipaters in dams consider as expensive structures; therefore, economic design of these structure are desirable.Stepped spillways can be use as energy dissipater to reduce the size and cost of the stilling basin. Hard experimental works, high-cost and time-consuming laboratory methods brought about some difficulties to determine the most-efficient design of the steps. This research deals with comparing the two-dimensional numerical simulation and experimental description in stepped spillways equipped with inclined steps and end sill together and presents a quick, trustworthy, economical, and numerical approach to designing the steps. In complicated geometries, simulation is more problematic than simulation of flow in horizontal steps, because it needs more precision around the end sills. Finite volume method and the k-ε standard model are proposed to simulate the flow pattern and evaluate the energy loss over stepped spillway. The flow pattern and velocity vectors resulted from numerical simulation is in a good agreement with the experimental results. Also, energy losses resulted from the numerical approach have been compared with laboratory measurements and demonstrate reasonable agreement.

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Volume of Fluid Model for Turbulence Numerical Simulation of Stepped Spillway Overflow

Cited by 138 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

Analysis of Two Phase Flows on Stepped Spillways

Energy Loss Estimation and Flow Simulation in the skimming flow Regime of Stepped Spillways with Inclined Steps and End Sill: A Numerical Model

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