Unsteady open-channel flows over rough bed with and without emergent rigid vegetation: A laboratory experiment

Khuntia, Jnana Ranjan; Proust, Sébastien; Khatua, Kishanjit Kumar

doi:10.1201/b22619-212

Cited by 2 publications

(1 citation statement)

References 8 publications

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“…Two turbulence characteristics, i.e., mean kinetic energy and turbulent kinetic energy will be calculated and analyzed for the same flow conditions. The variations of these two turbulent characteristics along the three given sections have been demonstrated (Khuntia et al 2018a(Khuntia et al , 2019(Khuntia et al , 2020.…”

Section: Experimental Set-up and Proceduresmentioning

confidence: 88%

Turbulence Characteristics in a Rough Open Channel Under Unsteady Flow Conditions

et al. 2021

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The majority of open channel flows of interest to hydraulic engineers and hydrologists are unsteady. In unsteady flow cases, some aspects of flow (velocity, depth, viscosity, pressure, etc.) will be evolving in time. However, more numbers of issues identified with the unsteady flow have been roughly accepting as steady flow (for example, constant peak discharges in floodplains). Very few experimental investigations have been conveyed in previous literature to examine turbulence qualities in an open channel flow under unsteady flow states over rough beds. The present study investigates the vertical and horizontal fluctuating velocity profiles under unsteady flow states in a rectangular open channel. An experiment is conducted to observe the turbulence characteristics under unsteady flow conditions in a rough bed open channel for two different flow depths. One identical hydrograph is passed repeatedly through the rectangular flume with a fixed rough bed. The dense rough mat is used as a rough bed which replica of a dense grass bed. The flow patterns are investigated at both lateral and longitudinal positions over three different cross-sections by using a micro Pitot tube and Acoustic Doppler Velocimeter (ADV). For two given flow depths, the velocities on both the rising and falling limbs are observed and analyzed. Hysteresis effect loop between stage-discharge (h ~Q) rating curve between the rising and falling limbs is illustrated. Turbulence characteristics, i. e., variations of lateral and vertical Reynolds stresses, are analyzed from measured fluctuation velocities.

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Section: Experimental Set-up and Proceduresmentioning

confidence: 88%

Turbulence Characteristics in a Rough Open Channel Under Unsteady Flow Conditions

et al. 2021

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Turbulence modelling for depth-averaged velocity and boundary shear stress of a dense rigid grass bed open channel

Sahoo,

Khuntia,

Devi

et al. 2023

AQUA — Water Infrastructure, Ecosystems and Society

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The present research focusses on a comparison of experimental and numerical approaches for flow over fixed artificial rigid grass bed channels. Various flow parameters like longitudinal velocity, depth-averaged velocity (DAV), boundary shear stress (BSS) and secondary current are analysed and compared with seven numerical models: standard, realizable and renormalization group (RNG) k–ε models and standard, shear stress transport (SST), generalized k–ω (GEKO) and Baseline (BSL) k–ω models. To evaluate the strength of the seven applied models, the error analysis has been performed. It is found that the RNG k–ε and SST k–ω models provided better results for both the DAV and BSS prediction, but the RNG k–ε model is found to be the most suitable for predicting the DAV and the SST k–ω model for BSS as compared to the other models. For the longitudinal velocity profiles, both the RNG k–ε and SST k–ω models are found to provide good agreement with experimental results at the centre of the channel, whereas the SST k–ω model is more accurate near the wall. Overall, the SST k–ω model has predicted the results with good accuracy for all the flow parameters considered in the present study.

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Unsteady open-channel flows over rough bed with and without emergent rigid vegetation: A laboratory experiment

Cited by 2 publications

References 8 publications

Turbulence Characteristics in a Rough Open Channel Under Unsteady Flow Conditions

Turbulence Characteristics in a Rough Open Channel Under Unsteady Flow Conditions

Turbulence modelling for depth-averaged velocity and boundary shear stress of a dense rigid grass bed open channel

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