A hybrid RANS-LES model for combining flows in open-channel T-junctions

Zeng, Cheng; Li, Chi Wai

doi:10.1016/s1001-6058(09)60186-4

Cited by 23 publications

(13 citation statements)

References 10 publications

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“…The strategies of 1D and 3D modeling could be applied to other flow diversion problems like river meander (Luo et al, 2018 The experimental data from Shumate (1998) [32], which included a 90° open-ch junction was used by Huang et al (2002) [12] to simulate the flow in an open con channel by developing and validating a three-dimensional numerical method. Rey The new modeling approach is more accurate than the RANS approach in addition to its ability of saving computational effort comparing to the LES approach (Zeng and Li, 2010) [26] Asymmetrical, Water 2021, 13, 1917…”

Section: Rans Modelsmentioning

confidence: 99%

Review and Comparison of Numerical Simulations of Secondary Flow in River Confluences

Shaheed

Yan

Mohammadian

2021

Water

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River confluences are a common feature in natural water resources. The flow characteristics in confluences are complicated, especially at junction areas between tributaries and the main river. One of the typical characteristics of confluences is secondary flow, which plays an important role in mixing, velocity, sediment transport, and pollutant dispersion. In addition to the experimental and field studies that have been conducted in this area, the development of computational fluid dynamics has allowed researchers in this field to use different numerical models to simulate turbulence properties in rivers, especially secondary flows. Nowadays, the hydrodynamics of flows in confluences are widely simulated by using three-dimensional models in order to fully capture the flow structures, as the flow characteristics are considered to be turbulent and three-dimensional at river junctions. Several numerical models have been recommended for this purpose, and various turbulence models have been used to simulate the flows at confluences. To assess the accuracy of turbulence models, flows have been predicted by applying different turbulence models in the numerical model and the results have been compared with other data, such as field, laboratory, and experimental data. The purpose behind these investigations was to find the suitable model for each case of turbulent flow and for different types of confluences. In this study, the performances of turbulence models for confluences are reviewed for different numerical simulation strategies.

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Section: Rans Modelsmentioning

confidence: 99%

Review and Comparison of Numerical Simulations of Secondary Flow in River Confluences

Shaheed

Yan

Mohammadian

2021

Water

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“…The latter aims at limiting the computational cost using LES only in relevant areas and solving stationary flow regions with a RANS model. Some authors use zonal RANS‐LES models to perform accurate LES computations in complex geometries like channel junctions (Zeng & Li, 2010) or vegetated areas (Li & Yu, 2010). This method is particularly efficient when unstable flow regions (i.e., regions featuring transient instabilities) are induced by geometric singularities.…”

Section: Introductionmentioning

confidence: 99%

Nonuniform Flows in a Compound Open‐Channel: Assessment of a Hybrid RANS‐LES Approach

Chatelain

Proust

2020

Water Resources Research

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Overbank flows in rivers, also termed compound open-channel flows, are rarely uniform in the streamwise direction. Flow nonuniformity involves transverse currents directed from the river main channel (MC) to adjacent floodplains (FPs) or vice versa. Depending on their direction and magnitude, the transverse currents can laterally displace the planform shear layer that forms at the interface between MC and FP. They can also modify the cross-sectional distribution of the helical secondary currents (SCs). This paper reports a numerical study that focuses on assessing the ability of a hybrid RANS (Reynolds Averaged Navier-Stokes)-LES (Large Eddy Simulation) approach, namely, the Scale Adaptive Simulation (SAS), to capture the evolving structure of both depth-uniform and nonuniform flows in a straight compound open-channel. The simulated flows have recently been studied in an 18 m long and 3 m wide laboratory flume by Proust and Nikora (2020, https://doi.org/10.1017/jfm.2019.973). The originality of the study lies in the modeling of flows over the entire flume length and in the estimate of the length-scales of the large Kelvin-Helmholtz-type coherent structures (KHCSs). The SAS approach can accurately predict the longitudinal evolution of: (i) the streamwise time-averaged flow, including the planform shear layer width, (ii) the SC patterns, and (iii) the turbulence statistics. The emergence and development of the KHCSs are qualitatively retrieved and are confirmed to be controlled by dimensionless velocity shear irrespective of flow depth. The simulations also show that SC patterns depend on the magnitude and direction of the transverse currents and also on the development of KHCSs.

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“…Many fluid simulation software programs have been proposed. In terms of numerical simulation theory [1][2][3][4][5][6] research, with turbulence model analysis and the turbulent kinetic energy equation having been put forward [7,8], an increasing number of high-precision numerical simulation techniques are used to simulate the complex flow in the side pump sump of a pumping station. The 3D unsteady turbulent flow in the sump has been simulated with four different turbulence models, namely, standard k-ε, realizable k-ε, renormalization group k-ε, and shear stress transfer k-ε volume of fluid (VOF) multiphase models [9].…”

Section: Introductionmentioning

confidence: 99%

Formation Mechanism of an Adherent Vortex in the Side Pump Sump of a Pumping Station

Wang¹,

Lü²

2021

Int. j. simul. model.

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The inflow of the side pump sump is not smooth enough during the operation of a pumping station, resulting in an asymmetric adherent vortex that endangers the station's normal operation and safety. To solve this problem, flow field and vorticity distribution charts of different flow layers were created through the establishment of a numerical model of the pumping station inflow by means of the fluid simulation software. The formation mechanism of the asymmetric adherent vortex in the side pump sump was analysed by combining Reynolds shear stress distribution, the simplified Navier-Stokes equation, and the transport equation of turbulent kinetic energy. Furthermore, the accuracy of the numerical simulation results was verified using flow field data collected via particle image velocimetry at the junction of the forebay and pump sumps of the station. Results show that the distribution of inflow velocity is uneven due to the asymmetric friction of the inflow in the side pump sump. The transverse velocity formed from it generates the asymmetric vortex in the side pump sump and creates an inspiratory vortex.

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A hybrid RANS-LES model for combining flows in open-channel T-junctions

Cited by 23 publications

References 10 publications

Review and Comparison of Numerical Simulations of Secondary Flow in River Confluences

Review and Comparison of Numerical Simulations of Secondary Flow in River Confluences

Nonuniform Flows in a Compound Open‐Channel: Assessment of a Hybrid RANS‐LES Approach

Formation Mechanism of an Adherent Vortex in the Side Pump Sump of a Pumping Station

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