Momentum transfer coefficients at the adjoining interfaces of a compound channel

Pradhan, S; Khatua, Kishanjit Kumar

doi:10.1016/j.flowmeasinst.2020.101792

Cited by 7 publications

(2 citation statements)

References 18 publications

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“…Recently, Pradhan and Khatua [47] evaluated the momentum transfer coefficients of compound channels with various roughness which was able to establish a new method to compute the discharge distribution in compound channels. Due to the complexity of the flow mechanisms in compound channels, the flow discharge in these cases at a given flow depth is not as easily predicted as for single channels.…”

Section: Overview Of the Mechanisms Of Overbank Flowsmentioning

confidence: 99%

Apparent roughness coefficient in overbank flows

Fernandes

2021

SN Appl. Sci.

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Overbank flows occur in alluvial valleys during flood events when the conveyance of main channel of rivers is exceeded. Once floodplains are inundated and the so-called compound channel flow is observed, the faster flow in the main channel interacts with the slower flow in the floodplain featuring a much more pronounced 3D flow structure compared to single channel flow. These flow mechanisms comprise a shear layer near the interface, lateral momentum transfer and strong secondary currents due to the non-isotropic turbulence. This paper starts by giving an overview of the main flow mechanisms in compound channels pointing out the importance of taking into account the apparent shear stress generated between the main channel and the floodplain flows due to the interaction of these flows. A new simple model was developed to include the apparent shear stress concept as a correction of the Manning roughness coefficient of main channel and floodplains. The proposed method for predicting stage–discharge relationships was calibrated and validated by experimental data from several compound channel facilities. A significant improvement in prediction of the compound channel conveyance in comparison with the traditional methods was achieved.

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Section: Overview Of the Mechanisms Of Overbank Flowsmentioning

confidence: 99%

Apparent roughness coefficient in overbank flows

Fernandes

2021

SN Appl. Sci.

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“…Various models and approaches have been proposed in the literature to define and predict flow characteristics at the interface of vegetated channels. Some of these studies include simplified one-dimensional approaches and the Darcy-Weisbach friction factor (Helmiö, 2004), while others treat the channel as a single or divided channel, using standard Chezy, Manning and Darcy-Weisbach equations to divide the section into non-interacting subareas either horizontally, vertically or diagonally (Ferro, 2019;Pradhan and Khatua, 2020;Tang, 2017;Wang et al, 2009;Wang et al, 2022;Yang et al, 2019). posit that the active turbulence and structured movements near the top of a vegetation canopy follow the pattern of a plane mixing layer.…”

Section: Introductionmentioning

confidence: 99%

Analysis of open channel flow with various layered vegetation using CFD, considering different near-wall treatment methods

Şibil

2024

HFF

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Purpose The purpose of this paper is to investigate the impact of near-wall treatment approaches, which are crucial parameters in predicting the flow characteristics of open channels, and the influence of different vegetation covers in different layers. Design/methodology/approach Ansys Fluent, a computational fluid dynamics software, was used to calculate the flow and turbulence characteristics using a three-dimensional, turbulent (k-e realizable), incompressible and steady-flow assumption, along with various near-wall treatment approaches (standard, scalable, non-equilibrium and enhanced) in the vegetated channel. The numerical study was validated concerning an experimental study conducted in the existing literature. Findings The numerical model successfully predicted experimental results with relative error rates below 10%. It was determined that nonequilibrium wall functions exhibited the highest predictive success in experiment Run 1, standard wall functions in experiment Run 2 and enhanced wall treatments in experiment Run 3. This study has found that plant growth significantly alters open channel flow. In the contact zones, the velocities and the eddy viscosity are low, while in the free zones they are high. On the other hand, the turbulence kinetic energy and turbulence eddy dissipation are maximum at the solid–liquid interface, while they are minimum at free zones. Originality/value This is the first study, to the best of the author’s knowledge, concerning the performance of different near-wall treatment approaches on the prediction of vegetation-covered open channel flow characteristics. And this study provides valuable insights to improve the hydraulic performance of open-channel systems.

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