Supercritical flow over a rectangular side weir

2003 ◽  
Vol 30 (3) ◽  
pp. 596-600 ◽  
Author(s):  
Masoud Ghodsian
Keyword(s):  
Discharge Coefficient ◽  
Hydraulic Characteristics ◽  
Height Ratio ◽  
Side Weir ◽  
Supercritical Flow ◽  
Urban Sewage ◽  
Land Drainage ◽  
Weir Height ◽  
Side Weirs ◽  
Sewage Systems

Side weirs are flow-diversion devices widely used in irrigation, land drainage, and urban sewage systems. Hydraulic characteristics of a sharp-crested rectangular side weir under supercritical flow have been studied in this paper. The concept of elementary discharge coefficient for supercritical flow is introduced. The elementary discharge coefficient has been related to head weir height ratio and local Froude number. Suitable equations for the elementary discharge coefficient are introduced.Key words: supercritical flow, sharp crested, rectangular side weir, elementary discharge coefficient.

scholarly journals Determination Discharge Capacity of Triangular Labyrinth Side Weir Using Multi-Layer Neural Network (ANN-MLP)

2015 ◽  
Vol 10 (Special-Issue1) ◽  
pp. 111-119 ◽  
Author(s):  
Sohrab Karimi ◽  
Hossein Bonakdari ◽  
Azadeh Gholami
Keyword(s):  
Discharge Capacity ◽  
Discharge Coefficient ◽  
Vertex Angle ◽  
Hydraulic Parameters ◽  
Side Weir ◽  
Dimensionless Parameters ◽  
Weir Height ◽  
Crest Length ◽  
Side Weirs ◽  
Mlp Model

statistic indexes have been used to assess the accuracy of the results. The results of the examinations indicate that using MLP model along with simultaneous use of dimensionless parameters for the purposes of estimating discharge coefficient: the ratio of water behind the weir to the channel width (h/b), ratio of weir crest length to weir height (L/W), relative Froude number (F=V/√(2Side weirs are used in open channels to control flood and the flow passing through it. Discharge capacity is one of the crucial hydraulic parameters of side weirs. The aim of this study is to determine the effect of the intended dimensionless parameters on predicting the discharge coefficient of triangular labyrinth side weir. MAPE, RMSE, and Rgy)) and vertex angle (ϴ), offered the best results (MAPE= 0.67, R2= 0.99, RMSE = 0.009) in comparison with other models.

scholarly journals Flow Over Side Weirs with Experimental & CFD Results

2019 ◽  
Vol 9 (1) ◽  
pp. 1315-1319
Keyword(s):  
Hydraulic Control ◽  
Plan View ◽  
Side Weir ◽  
Urban Sewage ◽  
Land Drainage ◽  
Diversion Structure ◽  
Coefficient Of Discharge ◽  
Crest Length ◽  
Side Weirs ◽  
Discharging Capacity

In irrigation, sewer systems and drainage engineering side weirs are used to as a hydraulic control structure from many decades. Labyrinth side weir is a side weir with increased crest length due to folding in plan view as it provides additional length for a given opening. As a flow diversion structure in irrigation, land drainage, urban sewage systems and in intake structures. Labyrinth side weirs can be used more efficiently than conventional side weirs. In this review paper some investigations of researchers with different parameter affecting coefficient of discharge and discharging capacity of side weirs are presented. In review it seems that different parameters are affecting on discharge of side weir has been considered in empirical equations given by researcher but few parameters are left for consideration. In this paper effect of additional parameters like side weir thickness and submergence condition is evaluated by CFD mo

scholarly journals Investigation of trapezoidal sharp-crested side weir discharge coefficients under subcritical flow regimes using CFD

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Amir Ghaderi ◽  
Mehdi Dasineh ◽  
Saeed Abbasi ◽  
John Abraham
Keyword(s):  
Discharge Coefficient ◽  
Effective Parameters ◽  
Side Weir ◽  
Discharge Coefficients ◽  
Weir Height ◽  
Crest Length ◽  
Side Weirs ◽  
Upstream Flow ◽  
Water Elevation ◽  
Correlation Factors

AbstractSide weirs are utilized to regulate water surface and to control discharge and water elevation in rivers and channels. Here, the discharge coefficient for trapezoidal sharp-crested side weirs (TSCSW) and their affecting parameters are numerically investigated. To simulate the hydraulic and geometric characteristics of TSCSWs, three weir crest lengths of 15 cm, 20 cm and 30 cm with lengths of 20 cm, 30 cm and 40 cm and with two different sidewall slopes are utilized. The results show that for constant P/B (P: weir height, B: main channel width), the depth of flow along the channel and weir decreases as the crest length increases. Also, with increasing P/y1 ratio (P: weir height, y1: upstream flow depth), the discharge coefficient decreases for small crest lengths and increases for large crest lengths. The results show that for constant T/L ratio (T: passing flow width, L: side weir crest length), increasing the length, height and sidewall slope of a side weir will increase the discharge coefficient. It is observed that as the upstream Froude number increases for side weirs with longer crest lengths, the intensity of deviating flow and kinetic energy over the TSCSW will increase. Finally, some relations with high correlation factors are proposed for obtaining discharge coefficients using the dimensionless parameters of P/y1, T/L and Fr1. Based on proposed relations and sensitivity analysis, it is shown that T/L and P/y1 are the most effective parameters for reducing the discharge coefficient reduction.

scholarly journals The Effect of Geometric Parameters of the Antivortex on a Triangular Labyrinth Side Weir

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 14
Author(s):  
Saeed Abbasi ◽  
Sajjad Fatemi ◽  
Amir Ghaderi ◽  
Silvia Di Francesco
Keyword(s):  
Discharge Coefficient ◽  
Flow Characteristics ◽  
Vertical Axis ◽  
Secondary Flows ◽  
Water Levels ◽  
Effective Length ◽  
Side Weir ◽  
Hydraulic Conditions ◽  
Weir Height ◽  
Side Weirs

Side weirs are important structural measures extensively used, for instance, for regulating water levels in rivers and canals. If the length of the opening is limited, the amount of water diverted out of the channel and the effective length can be increased by applying a labyrinth side weir. The present study deals with numerical simulations regarding the hydraulic performance of a labyrinth side weir with a triangular plan in single-cycle mode. Specifically, six different types of antivortexes embedded inside it and in various hydraulic conditions at different Froude numbers are analyzed. The antivortexes are studied using two groups, permeable and impermeable, with three different heights: 0.5 P, 0.75 P, and 1 P (P: Weir height). The comparison of the simulated water surface profiles with laboratory results shows that the numerical model is able to capture the flow characteristics on the labyrinth side weir. The use of an antivortex in a triangular labyrinth side weir reduces the secondary flows due to the interaction with the transverse vortexes of the vertical axis and increases the discharge capacity by 11%. Antivortexes in a permeable state outperform those in an impermeable state; the discharge coefficient in the permeable state increases up to 3% with respect to the impermeable state. Finally, based on an examination of the best type of antivortex, taking into account shape, permeability, and height, the discharge coefficient increases to 13.4% compared to a conventional labyrinth side weir.

Comparison of Subcritical and Supercritical Flow Patterns Within Triangular Channels Along the Side Weir

2016 ◽  
Vol 17 (7-8) ◽  
pp. 361-368 ◽  
Author(s):  
Hamed Azimi ◽  
Saeid Shabanlou
Keyword(s):  
Flow Regime ◽  
Transverse Velocity ◽  
Longitudinal Velocity ◽  
Side Weir ◽  
Supercritical Flow ◽  
Subcritical Regime ◽  
Triangular Channel ◽  
Diversion Channel ◽  
Side Walls ◽  
Side Weirs

AbstractSide weirs with triangular channel are used as flow controlling devices in draining and irrigation networks. By installing a side weir on the main conduits side walls, the runoff overflows from the weir and are conducted toward the diversion channel. In this study, changing of the flow free surface and the turbulence of the flow field in triangular channels with side weir are numerically simulated using volume of fluid (VOF) scheme and RNG k–ε turbulence model. In the present paper, the pattern of the spatially varied flow with decreasing discharge in both subcritical and supercritical flow regimes for triangular channels with side weirs was simulated. The present numerical model has precisely predicted the changes of the water surface and the specific energy. In subcritical regime, the flow depth is from the beginning of the weir toward its end is followed by an increase and in supercritical conditions is followed by a reduction in depth. For both subcritical and supercritical regimes, a drop in the surface in the first third of the weir’s opening and a surface jump in the final third of its length has occurred. Along the mentioned surface jump the amount of the kinetic energy increases and the potential energy reduces. According to results of the simulation, the maximum longitudinal velocity for subcritical flow regime occurs in the first third of the length of the side weir and for supercritical flow regime, almost in the middle of the weir opening happens. In both subcritical and supercritical regimes, the maximum transverse velocity has occurred in the final third of the length of the side weir.

Design Procedure for Side Weir in Triangular Channel

1992 ◽  
Vol 26 (5-6) ◽  
pp. 1275-1281
Author(s):  
A. Uyumaz
Keyword(s):  
Design Procedure ◽  
Level Control ◽  
Side Weir ◽  
Urban Sewage ◽  
Triangular Channel ◽  
Excess Water ◽  
Canal Systems ◽  
Surface Profiles ◽  
Side Weirs ◽  
Energy Principles

Side weirs have been used extensively for water-level control in irrigation and drainage canal systems, as a means of diverting excess water into relief channels for flood protection works, and as storm overflows from urban sewage systems. In this study, flow over side weir in triangular channel is reported. Theoretical model is obtained from energy principles and is solved by a finite difference method. The results are presented in diagrammatic form for practical use. The study covers both sub-and supercritical flow regimes. Derived expressions for the water surface profiles for these regimes are compared with experimental results.

Numerical Simulation of Free Surface and Flow Field Turbulence in a Circular Channel with the Side Weir in Subcritical Flow

2017 ◽  
Vol 18 (3-4) ◽  
pp. 255-267 ◽  
Author(s):  
Hamed Azimi ◽  
Saeid Shabanlou
Keyword(s):  
Numerical Simulation ◽  
Free Surface ◽  
Discharge Coefficient ◽  
Main Channel ◽  
Surface Discharge ◽  
Water Supply Systems ◽  
Circular Channel ◽  
Side Weir ◽  
Urban Sewage ◽  
Sharp Crest

AbstractWhen flow surface is higher than of a side weir crest, the overflow spilt over the crest and divert into a side channel. These structures are extensively used in urban sewage disposal networks, water supply systems, and drainage and flood diversion networks. This study simulates stream free surface, discharge over a sharp-crest side weir, and discharge coefficient of a side weir in a circular channel using FLOW-3D software. Numerical model results were compared with the experimental ones and the comparison proved an acceptable consistency between the numerical and experimental results. RNG k-ε turbulence model was used for simulating flow turbulence. The volume of fluid (VOF) method was used in this CFD analysis for predicting changes of flow free surface. Then, the numerical simulation results were examined for discharge coefficient of the side weir and flow free surface for different discharge passing through the main channel. The changes of dividing stream surface from main channel bed toward stream free surface were examined. The concluding section assessed the effect of shape of a circular channel on the pattern and intensity of a secondary flow in the main channel and the impacts of the discharge passing through the circular channel on height of stagnation point and shear stress pattern in the main channel bed.

scholarly journals Laboratory Investigation on Discharge Coefficient of Trapezoidal Piano Key Side Weirs

2019 ◽  
Vol 5 (6) ◽  
pp. 1327-1340 ◽  
Author(s):  
Minasadat Seyedjavad ◽  
Seyed Taghi Omid Naeeni ◽  
Mojtaba Saneie
Keyword(s):  
Laboratory Investigation ◽  
Water Surface ◽  
Discharge Coefficient ◽  
Hydraulic Structure ◽  
Side Weir ◽  
Labyrinth Weir ◽  
Dam Reservoirs ◽  
Water Conveyance ◽  
The One ◽  
Side Weirs

A spillway is a hydraulic structure used to provide the controlled release of surplus waters and floods from a dam into a downstream area. A side weir is a multipurpose hydraulic structure which is constructed in water conveyance systems with a height lower than that of the canal wall. When the water surface level goes up, the side weir regulates the discharge and controls the water surface in the main canal. Besides, the side weir controls and diverts floods in dam reservoirs, diverts the flow and protects the structure against the river inundations. In this research, a laboratory investigation is performed with 16 Type-A piano key weirs and three different pier heights of 10, 15 and 20cm. These weirs are studied for two cases of 1 and 2. The results show that the weirs with 15cm and 20cm heights in both cases 1 and 2 have the highest discharge coefficient  in dimensionless ratios of 0.2> H/P> 0.4 and H/P>0.5 respectively. Having reviewed previous studies, it could be concluded that the trapezoidal piano key side weir is capable of releasing a flow 1.2 times more than that of the linear trapezoidal labyrinth weir with 12 degrees angle and 1.87 times more than the one with 6 degrees angle, and 1.5 times more than that of the triangular labyrinth weir.

scholarly journals Discharge Coefficient of a C-Type Piano Key Side Weir at 30° and 120° Sections of a Curved Channel

2018 ◽  
Vol 4 (7) ◽  
pp. 1702 ◽  
Author(s):  
Yaser Mehri ◽  
Jaber Soltani ◽  
Mojtaba Saneie ◽  
Mohhamad Rostami
Keyword(s):  
Flood Control ◽  
Discharge Coefficient ◽  
Empirical Relationship ◽  
Effective Parameters ◽  
Level Control ◽  
Side Weir ◽  
Space Limitation ◽  
The Mean ◽  
Coefficient Of Discharge ◽  
Side Weirs

A piano key side weir (PKSW) is a non-linear weir that discharge exceeds linear weirs by increasing the length in width. PKSW can be used in side weirs with space limitation. As side weirs are extensively used in flood control, water level control in rivers, and water supply channels, it is necessary to use PKSW as side weirs. This research discusses the discharge coefficient of a PKSW by assessing a C-type PKSW at 30° and 120° sections of a channel with a longitudinal curve. Dimensional analysis was used for identifying the parameters effective in the discharge coefficient. The effects of these parameters are examined by analysing the effective parameters. Finally, an empirical relationship has been proposed for determining the discharge coefficient based on the dimensionless parameters for calculating the discharge coefficient with the correlation coefficient of 0.88 and the mean error of 0.091. The influence of the parameter on the PKSW is more than that of the remaining parameters: With an increase in the value of this parameter, considering decreases in the length of the deviation and a lack of submerged inlet keys, the coefficient of discharge increases.

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