Combined-free flow over weirs and below gates

Negm, Abdelazim M.; Al-Brahim, A.M.; Alhamid, A.A.; Sakarya, B. Altan; Aydin, İsmail; Ger, A. Metin

doi:10.1080/00221686.2004.9641225

Cited by 7 publications

(4 citation statements)

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“…Where H: upstream water depth, h: weir water head, y: vertical distance between weir and gate, d: gate opening height, A: gate cross section flow area, V: flow velocity, f: focal distance, b: Rectangular weir width, θ: Notch angle, g: acceleration due to gravity, Q_w ∶weir discharge, Q_g: Gate discharge, Q_theor: Theoretical discharge, Q_act: Actual discharge, c_d: Coefficient of discharge, the Reynolds number and Froude number are calculated by using the following equations [10,11]:…”

Section: (14)mentioning

confidence: 99%

Experimental Investigation of Multi Obstacles Impact on Weir-Gate Discharge Structure

2021

IJOMAM

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The flow over and under weir-gate structure that is placed inside a flume with obstacles downstream is studied experimentally. The distance between the first obstacle and weir-gate structure as well as the spacing between the obstacles are both considered constant. The goal of the present research paper is to characterize the interference between the weir-gate structure and the emerged square-shaped obstacle. The computation results show that the obstacles have a major role on dominating the trend between the several hydraulic variables. For instance, the relation between the discharge coefficient and upstream Froude number is adverse to the relation between the discharge coefficient and downstream Froude number. The increase of actual discharge leads to an increase in discharge coefficient. However, there is a dramatic trend in relation between the flow velocity at downstream and discharge coefficient. Another noticeable dramatic trend shown between the average downstream water depth and the discharge coefficient. In addition, it is found that there is a nonlinear trend in relation to Reynolds number and discharge coefficient. The present work discovered the impact of the flow across sectional area, which crosses the gate on the actual discharge and discharge coefficient, considering the number of obstacles at downstream regime with various obstacle thickness. Generally, any alteration in hydraulic response of weir-gate structure is attributed to the presence of obstacles at downstream of hydraulic regime, regardless of the number of obstacles and their dimensions.

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Section: (14)mentioning

confidence: 99%

Experimental Investigation of Multi Obstacles Impact on Weir-Gate Discharge Structure

2021

IJOMAM

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“…Similarly, different discharge equations are used if a weir is operating freely, as in stages 3 and 4, or if it is submerged, as in stage 5. Although in reality the gate and weir flows will interact [63][64][65], the interaction is ignored in the present study, and the gate and weir discharges are simply added together.…”

Section: Conceptual Modelmentioning

confidence: 99%

Modelling the Impact of Leaky Barriers with a 1D Godunov-Type Scheme for the Shallow Water Equations

Leakey

Hewett

Glenis

et al. 2020

Water

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There is increasing interest in distributing small-scale interventions across the landscape as an alternative means of reducing flood risk. One such intervention, the leaky barrier, is introduced in channels to slow down high flows and encourage temporary storage on the floodplain. While these barriers have been implemented widely, there is still resistance to their use at the scales required to impact significantly on flood risk, at least partially due to an evidence gap. In particular, there is no standard method for representing leaky barriers in hydraulic models. This study sets out a methodology for developing mathematical models which capture the hydraulics of leaky barriers accurately, allowing key questions about their combined behaviour in catchments to be answered. A 1D Godunov-type scheme is set up and leaky barriers incorporated with internal boundary conditions. This model is tested against benchmarks from the literature and new steady-state data, and then run predictively on transient cases. The method will help to answer key questions about the optimal leakiness of small-scale interventions, the limits to their usefulness, and how combinations of barriers may or may not cause synchronisation problems when the effect of multiple barriers is aggregated.

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“…These are obstructions generally placed normal to the direction of flow. A combined weir and gate structure shown in Figures 1(b) and 2 is a relatively new system suggested by several researchers, compared to extensive use of weirs and gates individually (Alhamid, 1999; Ferro, 2000; Negm et al, 2002; Altan‐Sakarya et al, 2005; Askeroğlu, 2006; Altan‐Sakarya and Kokpinar, 2013). In the combined system studied, the gate is comprised of a rectangular opening while the weir part has a trapezoidal cross section, as given by Askeroğlu (2006).…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of contracted sharp‐crested weirs and combined weir and gate systems

Altan‐Sakarya

Kökpinar

Duru

2020

Irrigation and Drainage

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Discharge measurement and control structures are widely employed in hydraulic engineering applications. The objective of this study is to numerically investigate the modelling of two different structures, namely sharpcrested weirs as Problem 1 and combined weir and gate systems as Problem 2. The research methodology herein is based on the comparison of results of numerical simulations with experimental data for both problems separately. For the purpose of performing numerical simulations, the Reynolds-averaged Navier-Stokes (RANS) equations are solved by finite volume formulation using commercially available Flow-3D software. Assessment of empirical data and numerical findings for both problems reveals that discharge rates agree reasonably well. In addition, using the capabilities of numerical modelling, weir and gate discharge coefficients in the combined system are calculated separately which were not easy to obtain in experimental studies. It is seen that gate and weir discharge coefficients of the combined system are different and higher than the corresponding coefficients of the individual systems. K E Y W O R D S combined weir and gate system, discharge measurement, Flow-3D, numerical simulation Résumé Les structures de mesure et de contrôle du débit sont largement utilisées dans les applications de génie hydraulique. L'objectif de cette étude est d'étudier numériquement la modélisation de deux structures différentes, à savoir des seuils à crête vive comme problème 1 et des systèmes de seuil et de barrière combinés comme problème 2. La méthodologie de recherche ici est basée sur la comparaison des résultats de simulations numériques avec des données expérimentales pour les deux problèmes séparément. Dans le but d'effectuer des simulations numériques, les équations de Reynolds-averaged Navier-Stokes (RANS) sont résolues par formulation de volumes finis à l'aide du logiciel Flow-3D disponible dans le commerce. L'évaluation des données empiriques et des résultats numériques pour les deux problèmes révèle que les taux de rejet concordent assez bien. De plus, en utilisant les capacités de la *Modélisation numérique des seuils à crête vive contractés et des systèmes combinés de seuils et de vanes.

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Combined-free flow over weirs and below gates

Cited by 7 publications

References 0 publications

Experimental Investigation of Multi Obstacles Impact on Weir-Gate Discharge Structure

Experimental Investigation of Multi Obstacles Impact on Weir-Gate Discharge Structure

Modelling the Impact of Leaky Barriers with a 1D Godunov-Type Scheme for the Shallow Water Equations

Numerical modelling of contracted sharp‐crested weirs and combined weir and gate systems

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