Comparing the Scour Upstream of Circular and Square Orifices

Hajikandi, Hooman; Vosoughi, Hassan; Jamali, Saeed

doi:10.1007/s40999-017-0269-5

Cited by 8 publications

(4 citation statements)

References 23 publications

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“…The underestimation of the flushing cone volume by Equation ( 4) could be due to the difference in the shape of the outlets, since Meshkati et al (2010) used circular outlets, whereas square and flat rectangular outlets were used in this study. Hajikandi et al (2018) and Dreyer and Basson (2018) had shown that square and flat rectangular outlets produce bigger flushing cones than the circular one. However, Equation (6) also considers outlet's shape in terms of b oc and b oe but still under-estimated the flushing cone volumes.…”

Section: Comparison Of Past Empirical Relationsmentioning

confidence: 98%

“…However, the flushing cone size not only depends on the opening area of the outlet, but also on its shape. For the outlets with the equivalent opening area, square outlets produce bigger flushing cones than circular outlets (Dreyer and Basson 2018;Hajikandi et al 2018) but smaller flushing cones than flat rectangular outlets (Dreyer and Basson 2018). For an outlet of specific shape and size, the maximum flushing efficiency can be achieved by flushing at the lowest operational reservoir level, while the bottom outlets are fully opened (Emamgholizadeh et al 2006;Meshkati et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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Physical modelling of pressure flushing of sediment using lightweight materials

Karmacharya

Rüther²,

Aberle

et al. 2021

Journal of Applied Water Engineering and Research

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While designing physical hydraulic model tests to investigate the efficiency of pressure flushing, it is most likely that very fine sediments of cohesive nature are required to satisfy the relevant scaling criteria. Cohesive sediments have different physical properties than sand, and a possibility to avoid such scale effects is to use lightweight materials with a specific gravity larger than water but lower than sand as model sediment. This paper addresses this issue by presenting results from laboratory experiments mimicking pressure flushing through a bottom outlet by using different lightweight materials and sand as model sediments. The results consolidate conclusions of previous studies carried out solely with sand and show that lightweight models can be used to predict the length and volume of flushing cones. Empirical relations to predict the length and volume of flushing cones are proposed and validated against a small set of experimental data from a previous study.

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Section: Comparison Of Past Empirical Relationsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Physical modelling of pressure flushing of sediment using lightweight materials

Karmacharya

Rüther²,

Aberle

et al. 2021

Journal of Applied Water Engineering and Research

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“…More empirical equations have been developed by, e.g., [34,35,[37][38][39]. Refer also to [32] for a more detailed review.…”

Section: Pressure Flushingmentioning

confidence: 99%

Hydraulic Flushing of Sediment in Reservoirs: Best Practices of Numerical Modeling

Lai,

Huang,

Greimann

2024

Fluids

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This article provides a comprehensive review and best practices for numerically simulating hydraulic flushing for reservoir sediment management. Three sediment flushing types are discussed: drawdown flushing, pressure flushing, and turbidity current venting. The need for reservoir sediment management and the current practices are reviewed. Different hydraulic drawdown types are described in terms of the basic physical processes involved as well as the empirical/analytical assessment tools that may be used. The primary focus has been on the numerical modeling of various hydraulic flushing options. Three model categories are reviewed: one-dimensional (1D), two-dimensional (2D) depth-averaged or layer-averaged, and three-dimensional (3D) computational fluid dynamics (CFD) models. General guidelines are provided on how to select a proper model given the characteristics of the reservoir and the flushing method, as well as specific guidelines for modeling. Case studies are also presented to illustrate the guidelines.

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“…General purposes of physical hydraulic modeling are reproduction and/or duplication of actual flow phenomena in a laboratory. us, with the help of successful physical hydraulic modeling, the effects of selected flow parameters around various hydraulic structures, such as different shape of orifices [1], T-shaped spur dike [2], bridge pier, and so on, can be examined using well-controlled laboratory experiment. is study is an experimental investigation of local pier scour throughout the reach of a bridge section under clear-water scour conditions using scale-down full bridge geometry and river bathymetry.…”

Section: Introductionmentioning

confidence: 99%

Reproducing Field Measurements Using Scaled-Down Hydraulic Model Studies in a Laboratory

Lee

Hong

2018

Advances in Civil Engineering

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Little efforts have been made to the value of laboratory model study in closing the gap between results from idealized laboratory experiments and those from field data. us, at first, three bridge sites were selected and equipped with fathometers to find the bed elevation change in the vicinity of bridge pier over time. After and during the flooding, the stream flow variables and their bathymetry were measured using current viable technologies at the field. en, to develop and suggest a laboratory modeling techniques, full three-dimensional physical models including measured river bathymetry and bridge geometry were designed and fabricated in a laboratory based on the scale ratio except for the sediment size, and the laboratory results were compared with the field measurements. Size of uniform sediment was carefully selected and used in the laboratory to explore the scale effect caused by sediment size scaling. e comparisons between laboratory results and field measurements show that the physical models successfully reproduced the flow characteristics and the scour depth around bridge foundations. With respect to the location of the maximum scour depth, they are not consistent with the results as in the previous research. Instead of occurring at the nose of each pier, the maximum scour depths are located further downstream of each pier column in several experimental runs because of the combination of complex pier bent geometry and river bathymetry, and the resulting unique flow motions around the pier bent.

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Comparing the Scour Upstream of Circular and Square Orifices

Cited by 8 publications

References 23 publications

Physical modelling of pressure flushing of sediment using lightweight materials

Physical modelling of pressure flushing of sediment using lightweight materials

Hydraulic Flushing of Sediment in Reservoirs: Best Practices of Numerical Modeling

Reproducing Field Measurements Using Scaled-Down Hydraulic Model Studies in a Laboratory

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