Discharge formula for rectangular sharp-crested weirs

Aydin, İsmail; Altan-Sakarya, A. Burcu; Sisman, Cigdem

doi:10.1016/j.flowmeasinst.2011.01.003

Flow Measurement and Instrumentation

2011

DOI: 10.1016/j.flowmeasinst.2011.01.003

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Discharge formula for rectangular sharp-crested weirs

İsmail Aydin

A. Burcu Altan-Sakarya

Cigdem Sisman³

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Cited by 81 publications

(49 citation statements)

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“…Generally, the discharge coefficient is a function of Reynolds number (Re), Weber number (We), H/P and H/B, where P is the height of the weir [1][2][3][4][5][6][7][8] . The following equations are suggested for the calculation of these numbers: Re = [(2gH) 0.5 (BH) 0.5 ]/ and We = (2gHB)/, where  the kinematic viscosity coefficient,  the density and  is the surface tension of water 4,9 .…”

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confidence: 99%

“…The following equations are suggested for the calculation of these numbers: Re = [(2gH) 0.5 (BH) 0.5 ]/ and We = (2gHB)/, where  the kinematic viscosity coefficient,  the density and  is the surface tension of water 4,9 . The valid international standards 10,11 and recent studies 2,4,12,13 recommend the equations listed in Table 1 for the discharge coefficient. These equations refer to ventilated nappe.…”

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confidence: 99%

“…Modifications in the discharge coefficient are, most likely, consequences of the impact of viscosity and the surface tension of water. The impact of Re and We on the discharge coefficient has also been checked during the testing of contracted thin-plate weirs for low discharges 2,16 . It has been concluded that there is no sufficiently strong relation between the discharge coefficient and Re, especially at fully contracted thin-plate weirs 2 .…”

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confidence: 99%

“…The impact of Re and We on the discharge coefficient has also been checked during the testing of contracted thin-plate weirs for low discharges 2,16 . It has been concluded that there is no sufficiently strong relation between the discharge coefficient and Re, especially at fully contracted thin-plate weirs 2 . In order to solve this problem, a factor for determining discharge Q/(B(P + H)) has been introduced instead of the discharge coefficient.…”

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confidence: 99%

“…The water temperature was 27C during the measurements. It has been Aydin et al 2 Gharahjeh et al 4 3/ 2 , 2 2 3…”

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confidence: 99%

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New Method for Discharge Hydrograph Measurement of the Free Overflow with Full-Width, Thin-Plate Weir

Hovány

2017

Current Science

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The current standards recommend measuring water discharge with vented thin-plate weirs. The ventilation of full-width, thin-plate weirs during discharge hydrograph measurement still poses a problem. An experimental study regarding the design of a new type of ventilating device for hydrograph measurement was performed from 20 October through 5 December 2015 which proved that this device can be used measuring discharge at ventilated nappe according to standard recommendations. During the second part of the experiment, an opportunity was provided for measuring the discharge at non-ventilated nappe as a function of Reynolds and Weber numbers.Keywords: Run-off hydrograph, water discharge, weirs, ventilated nappe.In the present study, water discharge in full-width thinplate weirs, in the case of non-submerged ventilated overflow is calculated using the equationwhere m is the discharge coefficient, B the width of the weir and H is the height of the nappe 1 . Generally, the discharge coefficient is a function of Reynolds number (Re), Weber number (We), H/P and H/B, where P is the height of the weir [1][2][3][4][5][6][7][8] . The following equations are suggested for the calculation of these numbers: Re = [(2gH) 0.5 (BH) 0.5 ]/ and We = (2gHB)/, where  the kinematic viscosity coefficient,  the density and  is the surface tension of water 4,9 . The valid international standards 10,11 and recent studies 2,4,12,13 recommend the equations listed in Table 1 for the discharge coefficient. These equations refer to ventilated nappe. For the height of the nappe H  0.03 m, the influence of Re and We on discharge is negligible 3 . For ventilation of the nappe, the literature recommends making holes beneath it in the channel walls, or using pipes for air supply 1,14 . The problem of ventilation occurs when the nappe separates from the weir due to the position of the holes, while the use of pipes requires blowing air in them. Studies conducted by the present author 1 also confirmed the existence of this problem. The simplest and most efficient ventilation of the nappe has been achieved by running a finger across it.In order to measure discharge using a thin-plate weir, a weir with dimensions B = 0.4 m wide and P = 0.341 m was tested 15 . It has been established that there is a nappe separation limit (H = 0.035 m) when the discharge increases, and a nappe adherence limit (i.e. when the nappe adheres to the thin-plate weir) when the discharge decreases (H = 0.009 m). Air for ventilation has been supplied by pipes and through holes on both sides of the channel. The holes on the channel walls are located at the middle of the weir, on the surface of the non-ventilated nappe. The following equations have been suggested for discharge coefficient calculations at water temperature of 11-14C.

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confidence: 99%

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confidence: 99%

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“…The water temperature was 27C during the measurements. It has been Aydin et al 2 Gharahjeh et al 4 3/ 2 , 2 2 3…”

mentioning

confidence: 99%

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New Method for Discharge Hydrograph Measurement of the Free Overflow with Full-Width, Thin-Plate Weir

Hovány

2017

Current Science

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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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Influence of irrigation water and soil on annual mercury dynamics in Sacramento Valley rice fields

Salvato,

Marvin‐DiPasquale,

Fleck

et al. 2024

J of Env Quality

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Methylmercury (MeHg) is a human and environmental toxin produced in flooded soils. Little is known about MeHg in rice (Oryza Sativa L.) fields in Sacramento Valley, California. The objectives of this study were to quantify mercury fractions in irrigation water and within rice fields and to determine their mercury pools in surface water, soil, and grain. Soil, grain, and surface water (dissolved and particulate) MeHg and total mercury (THg) were monitored in six commercial rice fields throughout a winter fallow season and subsequent growing season. Both dissolved and particulate mercury fractions were higher in fallow season rice field water. Total suspended solids and particulate mercury concentrations were positively correlated (r = 0.99 and 0.98 for THg and MeHg, respectively), suggesting that soil MeHg was suspended in the water column and potentially exported. Dissolved THg and MeHg concentrations were positively correlated with absorbance at 254 nm (r = 0.47 and 0.58, respectively) in fallow season field water. In the growing season, fields with higher irrigation water MeHg concentrations (due to recycled water use) had elevated field‐water MeHg (r = 0.86) and grain MeHg concentrations (r = 0.96). Based on a mass balance analysis, soil mercury pools were orders of magnitude larger than surface water or grain mercury pools; however, fallow season drainage and grain harvest were the primary pathways for MeHg export. Based on these findings, reducing (1) discharge when water is turbid, (2) straw inputs, and (3) use of recycled irrigation water could help reduce mercury exports in rice field drainage water.

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Discharge formula for rectangular sharp-crested weirs

Cited by 81 publications

References 7 publications

New Method for Discharge Hydrograph Measurement of the Free Overflow with Full-Width, Thin-Plate Weir

New Method for Discharge Hydrograph Measurement of the Free Overflow with Full-Width, Thin-Plate Weir

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

Influence of irrigation water and soil on annual mercury dynamics in Sacramento Valley rice fields

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