Prediction of scour downstream of triangular labyrinth weirs

Elnikhely, E.A.; Fathy, Ismail

doi:10.1016/j.aej.2020.03.025

Cited by 12 publications

(4 citation statements)

References 16 publications

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“…Noseda et al (2019) found that upstream scour can exceed the weir height (P). Elnikhely and Fathy (2020) proposed a prediction method for various apex angles for triangular labyrinth weirs with a downstream apron. They showed that labyrinth weirs produce less scour in comparison to linear weirs.…”

Section: Introductionmentioning

confidence: 99%

Evolution of local scour downstream of Type A PK weir in non-cohesive sediments

Lantz

Crookston

Palermo

2022

Journal of Hydrology and Hydromechanics

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A large-scale piano key weir laboratory study was conducted to investigate the evolution of the scour process occurring in the downstream basin for two non-cohesive granular bed materials, including the analysis of scour-hole geometry and patterns at equilibrium. It was observed that hydraulic conditions, particularly tailwater level, significantly affect the scour mechanisms and equilibrium morphology, eventually resulting in scour depths that exceeded the weir height. Unprecedented insights on the scour dynamics are also provided, along with tools to estimate the time evolution and maximum scour depth, its location in the streamwise direction, and the maximum scour length.

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Section: Introductionmentioning

confidence: 99%

Evolution of local scour downstream of Type A PK weir in non-cohesive sediments

Lantz

Crookston

Palermo

2022

Journal of Hydrology and Hydromechanics

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“…ℎ=normal depth (m), 𝑤 = scour factor which depends on the diameter of the sediment grains, 𝑑 90 where w = 22.88 s 0.6 /m 0.3 if 𝐷 90 in mm, ∆ℎ = difference in upstream and downstream energy levels (m), 𝑞 = discharge per unit width (m 3 /s 2 ) and 𝐷 90 = diameter of sediment particle 90% (mm). Another formula was also developed by Katoulas (1967) to predict the depth of scour by adding the gravitational acceleration parameter, as follows [16,17]:…”

Section: Methodsmentioning

confidence: 99%

Safety Assessment of Irrigation Weirs by Modeling Local Scour Potential Downstream of Energy Dissipator

Tunas,

Ishak,

Saparuddin

et al. 2024

IJSSE

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The phenomenon of local scour downstream of irrigation weir energy dissipators is one of the basic degradation problems in hydraulic structures on rivers. The hydraulic jump in the stilling basin, which is triggered by flow turbulence due to energy dampening, forms current vortices in horizontal and vertical directions. Eddy currents that are not fully controlled and damped in the stilling basin can cause scouring, especially in the vertical direction just downstream of the energy dissipators construction. Simultaneous accumulation of scour in the long term can endanger buildings around the weir, especially the stilling basin, both downstream wings and the main weir. This paper aims to assess weir safety by predicting scour characteristics under end sill energy dissipators using the hybrid model: HEC-RAS and Scour Empirical Equation. The simulation is carried out on three conditions, namely minimum, average and maximum discharges with input of sediment grain gradations obtained from field measurements. The three types of discharge are obtained from the transformation of daily rainfall into daily discharge using the HEC-HMS Model. The results of scour predictions in the 3 scenarios were compared with the results of scour measurements at the study location. The results of the study indicate that the greatest scour depth at the maximum discharge of almost 1.5 meters has reached the depth of the end sill of the energy dissipator. This prediction result was also verified by the observation scour depth of more than 1.5 meters. Observation results also show that the Energy Dissipator II has collapsed massively both in the center and on the left and right sides of the energy dissipator. Based on the results of the study and investigation, it can be concluded that the weir safety at the study location can be categorized as low with the potential for very large scour.

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“…The numerical result also gives a comprehensive representation of hydraulic features of the whole computational domain. A number of well-known Computational Fluid Dynamics (CFD) models including OpenFoam, Ansys Fluent, Flow 3D, etc., have been widely utilized in this field [8,[17][18][19]. These numerical models based on the coupling of the Volume Fluid Method and Navier Stokes equations have played important roles in simulating sediment scour issues due to the help of state-of-the-art 3D CFD models [10,20].…”

Section: Introductionmentioning

confidence: 99%

Numerical study of sediment scour at meander flume outlet of boxed culvert diversion work

Hien

Nguyen²,

2022

PLoS ONE

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Background Sediment scour at downstream of hydraulic structures is one of the main reasons threatening its stability. Several soil properties and initial input data have been studied to investigate its influence on scour hole geometry by both physical and numerical models. However, parameters of resistance affecting sedimentation and erosion phenomena have not been carried out in the literature. Besides, the auxiliary-like wing walls prevalently used in many real applications have been rarely addressed for their effect on morphological change. Results In this study, a 3D Computational Fluid Dynamics model is utilized to calibrate the hydraulic characteristics of steady flow going through the culvert by comparison with experimental data, showing good agreement between water depth, velocity, and pressure profiles at the bottom of the boxed culvert. The results show that a grid cell of 0.015 m gave minimum NRMSE and MAE values in test cases. Another approach is numerical testing sediment scour at a meander flume outlet with a variety of roughness/d50 ratio (cs) and diversion wall types. The findings include the following: cs = 2.5 indicates the close agreement between the numerical and analytical results of maximum scour depth after the culvert; the influence of four types of wing wall on the geometrical deformation including erosion at the concave bank and deposition at the convex bank of the meander flume outlet; and two short headwalls represent the best solution that accounts for small morphological changes. Conclusions The influence of the roughness parameter of soil material and headwall types on sediment scour at the meander exit channel of hydraulic structure can be estimated by the numerical model.

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Prediction of scour downstream of triangular labyrinth weirs

Cited by 12 publications

References 16 publications

Evolution of local scour downstream of Type A PK weir in non-cohesive sediments

Evolution of local scour downstream of Type A PK weir in non-cohesive sediments

Safety Assessment of Irrigation Weirs by Modeling Local Scour Potential Downstream of Energy Dissipator

Numerical study of sediment scour at meander flume outlet of boxed culvert diversion work

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