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1
Yousif, Omed S. Q., and Moses Karakouzian. "Effect of Corner Shape on Hydraulic Performance of One-Cycle Rectangular Labyrinth Weirs." Fluids 5, no. 3 (July 20, 2020): 117. http://dx.doi.org/10.3390/fluids5030117.
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The hydraulic performance of rectangular labyrinth weirs has been investigated by many researchers, however, the effects of the corner shape on the hydraulic performance of rectangular labyrinth weirs have not been addressed in the current literature. Accordingly, this experimental study aims to explore the effect of the corner shape of on discharge efficiency of rectangular labyrinth weirs. Five flat-crested rectangular labyrinth weirs, with five different corner shapes, were made of High-Density Polyethylene Plastic (HDPE) and tested in a rectangular flume. Under different overflow discharges, the discharge coefficients for the rectangular labyrinth weirs were determined. The results showed that the shape of corners for rectangular labyrinth weirs was an effective factor. For example, rounding or beveling the corners can significantly increase the discharge capacity of the rectangular labyrinth weirs. However, the rounded corner shape was slightly better than the beveled corner shape. Among all labyrinth weir models tested in this study, the rectangular labyrinth weir with a semi-circular apex showed the highest hydraulic efficiency, while the one with an acute-angle corner shape showed the lowest hydraulic efficiency. For the rectangular labyrinth weir having a semi-circular shape, although the original effective length reduced by about 14%, the discharge coefficient, CL, increased by 16.7% on average. For the rectangular labyrinth weir that has an acute-angle corner shape, although the effective length (LC) of the weir increased by 23%, its discharge capacity decreased by 35.2% on average. Accordingly, improper folding of the side-walls of the rectangular labyrinth weir led to a significant reduction in the weir’s hydraulic performance.
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Ghazizadeh, Farhad, and M. Azhdary Moghaddam. "An Experimental and Numerical Comparison of Flow Hydraulic Parameters in Circular Crested Weir Using Flow3D." Civil Engineering Journal 2, no. 1 (January 1, 2016): 23–37. http://dx.doi.org/10.28991/cej-2016-00000010.
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Circular crested weirs consist of a circular crested of upstream and downstream walls. These weirs are widely used in hydraulic engineering as water discharge structures and can be used to control water level in channels and tanks. In the present study, using Flow3D software, hydraulic properties were investigated to find weir geometry optimization through CFD method. Also, this study attempted to investigate flow on some sections of circular crested weirs in 3 groups and 11 models. Upstream and downstream slope changes as well as the height of the weir were also studied. To validate the model, laboratory models were used. In the research, flow depth parameters on crest, pressure distribution, velocity distribution, energy loss on circular crested weirs, as well as the height and changes of upstream and downstream slope were evaluated. Flow depth on the body of circular crest in this state is about 0.71 (H1). Upstream slope changes on flow depth on the weir’s crest revealed that increasing upstream slope causes to the increase of flow relative depth (H1/R) on the crest about 62%. Downstream changes in H1/R values less than 0.7 have no significant effect on discharge coefficient; however, increasing H1/R values seems to cause more change in slope.
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Emiroglu, M. "Estimating Flow Characteristics of Different Weir Types and Optimum Dimensions of Downstream Receiving Pool." Journal of Hydrology and Hydromechanics 58, no. 4 (December 1, 2010): 245–60. http://dx.doi.org/10.2478/v10098-010-0023-z.
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Estimating Flow Characteristics of Different Weir Types and Optimum Dimensions of Downstream Receiving PoolThis paper presents the results of a laboratory study on the flow characteristics of sharp-crested weirs, broad-crested weirs, and labyrinth weirs. The variation of the maximum bubble penetration depth for different weir types is investigated depending on overfall jet expansion, discharge, and drop height. Moreover, most efficient depth, length and width of the downstream receiving pool in an open channel system are studied by considering the penetration depth, overfall jet expansion, jet trajectory and the bubble zone. The results show that overfall jet expansion at the labyrinth weirs is significantly wider than the rectangular sharp-crested weirs and the trapezoidal sharp-crested weir. It is demonstrated that the labyrinth weirs have the lowest values of bubble penetration depth among the weirs tested. Furthermore, it is found that the rectangular and the trapezoidal weirs are observed to have the highest bubble penetration depth among all weirs. Consequently, empirical equations are obtained for predicting the maximum penetration depth of bubbles, trajectory of free overfall nappe, jet expansion of free overfall nappe, and the length of the bubble zone.
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Hussain, Ruqiya Abed, Sawsan Abdullah Hassan, and Asmaa Abdul Jabbar Jamel. "Experimental Study on Flow over Triangular Labyrinth Weirs." International Journal of Design & Nature and Ecodynamics 17, no. 2 (April 27, 2022): 249–55. http://dx.doi.org/10.18280/ijdne.170211.
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Recently, many research studies have focused on labyrinth weirs' hydraulic performance, especially as dependent on engineering features. In the current study, the hydraulic properties of flow over labyrinth triangular weirs models (from the upper perspective) with sharp crest have been experimentally studied and compare their efficiency with suppressed rectangular weirs (conventional weirs). Twelve fiberglass models are developed for this reason and tested in a 6m in length, 30cm in width, and 40cm height in laboratory flume, nine models were constructed for triangular labyrinth weirs and three models were constructed for suppressed rectangular weirs, Three alternative heights (p=15, 20, and 25cm) were employed in this research, for each height, the vertex angle (θ) changed three times (60օ, 90օ, 120օ), and for each one of these weirs was used, seven different discharge were approved. The overall tests in this study were 84. The dimensionless parameters on which the discharge coefficient (Cd) is dependent were obtained using dimensional analysis. parameters were plotted. According to this experimental present study, as compared to linear weirs, labyrinth triangular weirs shown to be more hydraulically efficient. Also, the height of the weir (P) has effects on the discharge coefficient, where (Cd) increased with decreasing (P). Also, the vertex angle of triangular labyrinth weirs(θ) has a major influence on discharge coefficient and on weir performance, where the discharge coefficient raises when decreases the value of angle(θ), in another means, when the angle decreases gave an increase in the path of the flow, where it gave the triangular labyrinth weir with an angle of 60o the discharge coefficient reached its greatest value (2.55), followed by the weir with an angle of 90o and 120o respectively. In other words (a small vertex angle gives more length effective (Le) to the weir) and this leads to an increase in flow capacity or performance for the weir.
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Yousif, Omed S. Q., Kawa Z. Abdulrahman, Wazira Qadir, Ahang S. Ali, and Moses Karakouzian. "Characteristics of Flow over Rectangular Labyrinth Weirs with Round Corners." Hydrology 8, no. 4 (October 18, 2021): 158. http://dx.doi.org/10.3390/hydrology8040158.
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The hydraulic performance of round-cornered rectangular labyrinth weirs with varying weir heights and effective lengths has not been explored in the existing literature to the authors’ knowledge. The purpose of this experimental study was to see how the height and effective length of round-cornered rectangular labyrinth weirs affect their discharge efficiency. Nine flat-crested rectangular labyrinth weirs made of high-density polyethylene (HDPE) were tested in a rectangular flume under various discharges to fulfill the goals of this study. The discharge coefficients for the weirs were then calculated. The hydraulic efficiency of weirs with round corners increases as the weir height (P) increases, according to the findings; however, with effective length of the weir to channel width ratios (LC/B) ≤ 1.78, the effect of the weir height diminishes. For the HT/P ranges used in this study, 0.1 ≤ HT/P ≤ 0.65, the round-cornered rectangular labyrinth weirs with higher LC/B ratios (greater M values) showed improved hydraulic efficiency. Furthermore, the effects of the round-cornered rectangular labyrinth weirs’ headwater inflation can be mitigated by increasing the effective length of the weirs;by increasing M values (LC/B ratios). Using multiple linear regression analysis, a satisfactory correlation equation was found between discharge coefficients of round-cornered rectangular labyrinth weirs, CB, and the other parameters, LC, P, and h.
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Kılıç, Zeyneb. "Geometric and Hydraulic Properties of Arced Labyrinth Weirs." International Journal of Current Engineering and Technology 12, no. 02 (April 2, 2022): 121–26. http://dx.doi.org/10.14741/ijcet/v.12.2.4.
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Weirs serve a critical role in dam safety. Numerous reservoirs' flood projections used in hydraulic design have risen in magnitude in recent years. As a result, many current spillways are no longer adequate since they do not fulfill current discharge capacity standards. Labyrinth weirs are frequently used to rehabilitate existing fixed width spillways. Weirs come in a variety of shapes and sizes, including labyrinth, linear, piano key, and more. Labyrinth weirs enhance the weir crest length for a given width, which increases the weir flow capacity. The majority of labyrinth weirs are designed in linear designs. An Arced cycle layout can boost the discharge capacity and hydraulic efficiency of a labyrinth weir. The article cites an arced geometric layout for labyrinth weirs, as well as nomenclature for arcspecific geometric variables. Experimental studies in the literature are presented by discussing and comparing.
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A, Abo A. "Performance Against Cavity Index and Discharge Coefficient between Broad and Sharp Crested Weirs." Polytechnic Journal 12, no. 1 (August 18, 2022): 103–7. http://dx.doi.org/10.25156/ptj.v12n1y2022.pp103-107.
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The purpose of this research is examining the performance of rectangular broad and sharp crested weirs in terms of cavity index and discharge coefficient. For this purpose, a computational fluid dynamics CFD code FLUENT is applied. Firstly, the code verified by applies on the experiments work of Hagre et al 1994 the results show excellent agreements between CFD and Hager et al 1994. Secondly the code applied on both broad and sharp crested weirs. The results demonstrate that broad crested weirs have a lower discharge coefficient than sharp crested weirs, implying that broad crested weirs have a lower ability to discharge flow than sharp crested weirs. While the cavity index of a broad crested weir is lower than that of a sharp crested weir, the risk of cavitation is lower for a broad crested weir. Finally, designers should use caution when deciding which type of crest to use in their designs.
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Rezazadeh, Shiva, Mohammad Manafpour, and Hamze Ebrahimnejadian. "Three-Dimensional Simulation of Flow Over Sharp-Crested Weirs Using Volume of Fluid Method." Journal of Applied Engineering Sciences 10, no. 1 (May 1, 2020): 75–82. http://dx.doi.org/10.2478/jaes-2020-0012.
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AbstractIn sharp crested weirs, significant changes occur in the hydraulic characteristics of the flow past the weirs with different geometry. A detailed investigation and better understanding of hydraulic behavior will help practically to choose an appropriate geometry for weir. The purpose of this research is simulate the flow over sharp crested weir and investigate the effect of geometric shapes of sharp crested weirs on hydraulic characteristics of the flow such as pressure, velocity, water level profiles and discharge coefficients. Thus the limitation and usage range of sharp crested weirs are clarified. In this research OpenFOAM open source 3D software with RNG K-ε turbulence model and Volume of Fluid method (VOF) was used to analyze the hydraulic flow passing through sharp crested weir. The correlation coefficient for flow Surface profiles and discharge coefficients among numerical and experimental data is obtained 0.96 for different discharge rates. In the present research, discharge coefficients for rectangular weirs with compression coefficient 0%, trapezoidal and triangular weirs are determined 1.20, 0.68 and 0.51 respectively using discharge rate of 0.05183m3/s. The maximum discharge coefficient is obtained for rectangular sharp crested weir while the triangular sharp crested weir has minimum discharge coefficient.
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Emiroglu, M. Emin, and Ahmet Baylar. "Experimental Study of the Influence of Different Weir Types on the Rate of Air Entrainment." Water Quality Research Journal 38, no. 4 (November 1, 2003): 769–83. http://dx.doi.org/10.2166/wqrj.2003.048.
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Abstract Aeration is used in water treatment to alter the concentration of dissolved gases, to strip volatile organics, and to reduce tastes and odours. This can be obtained by creating turbulence in the water. One method of producing such turbulence is via the overflow jets downstream of weir structures. This paper investigates the effect of varying weir types on the air entrainment rate. Empirical correlations predicting the maximum penetration depth and air entrainment rate were developed for different weir types. It is demonstrated that the air entrainment rate of the broad-crested weirs is generally much better than for the sharp-crested weir and the labyrinth weirs. The air entrainment rate increased as the weir longitudinal slope of the broad-crested weirs and the weir sill slope of the labyrinth weirs became larger.
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Tian, Zhong, Wei Wang, Ruidi Bai, and Nan Li. "Effect of Flaring Gate Piers on Discharge Coefficient for Finite Crest-Length Weirs." Water 10, no. 10 (September 28, 2018): 1349. http://dx.doi.org/10.3390/w10101349.
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The use of flaring gate piers (FGPs) along with finite crest-length weirs changes the shape of plunging jets and increases the efficiency of energy dissipation in some projects; however, the FGPs may affect the discharge capacity. In this study, the flow pattern and discharge coefficient were experimentally investigated under different conditions by varying the weir lengths Lw, contraction ratio β, contraction angle θ, and water heads H. A comparative analysis of the weirs with and without FGPs was performed. For the finite crest-length weirs with FGPs, the water-surface profiles in the flow channel were backwater curves. Moreover, the plunging jets leaving the weir became narrower and then subsequently diffused largely in the transverse and longitudinal directions in air. The discharge coefficients of the weirs with FGPs were approximately equal for various weir lengths. Moreover, following the earlier studies on traditional finite crest-length weirs, a discharge-coefficient equation was developed for the weir with an FGP in this study. The results showed that in the weirs with FGPs, the discharge coefficients clearly increased with the increase in the contraction ratio and water head, but the changes in their values along with the contraction angle were neglected.
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Moldovan, Aurelian Cosmin, Valer Micle, Tomi Alexandrel Hrăniciuc, and Nicolae Marcoie. "Research on the Sustainable Development of the Bistrita Ardeleana River through the Resizing of Weirs." Water 14, no. 20 (October 21, 2022): 3333. http://dx.doi.org/10.3390/w14203333.
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The layout of water resources and the complex and rational use of them have an important role in the socioeconomic activities of an urban settlement. Transversal hydrotechnical constructions such as weirs reduce the longitudinal connectivity of rivers and streams, affecting river biodiversity as well as water quality. This paper presents an alternative method that will help restore connectivity. In order to choose the best solution, topographical measurements were taken with a total topographical station, and a professional drone was used to obtain an updated orthophoto plan. After processing the data obtained in the field, engineering software capable of simulating flow, sediment transport, and water quality in rivers was used. With the help of the software, two hypotheses were realized: hypothesis A, the case with only one weir in place, and hypothesis B, when we have the proposed case with the lowering of the height of the weir’s crest and the construction of three new control weirs downstream of it. In conclusion, the lowering of the current weir’s crest and the construction downstream of it of three new weirs of low height would have a favorable effect from an ecological and a morphological point of view, without very big consequences on the disturbance of the flow from a hydraulic point of view.
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Neimanis, A. S., H. N. Koopman, A. J. Westgate, L. D. Murison, and A. J. Read. "Entrapment of harbour porpoises (Phocoena phocoena) in herring weirs in the Bay of Fundy, Canada." J. Cetacean Res. Manage. 6, no. 1 (March 16, 2023): 7–17. http://dx.doi.org/10.47536/jcrm.v6i1.784.
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Harbour porpoises (Phocoena phocoena) are small coastal cetaceans vulnerable to mortality in fishing operations. Not all interactions are fatal, however, and each year many porpoises swim into and are subsequently released from herring weirs in the Bay of Fundy, Canada through a targeted release programme. This study examines catch composition, body condition, characteristics associated with mortality and factors affecting entrapment of porpoises in weirs between 1992-2001. A total of 886 porpoises were recorded in weirs during this period. A total of 657 animals were involved in attempted releases: 588 were released alive and 69 were incidentally killed during release. The remainder of the animals swam out on their own or their fates were unknown. Estimated annual mortality represents less than 0.01% of the Bay of Fundy/Gulf of Maine population and only 1.03% of its annual potential biological removal level. The number of porpoises caught in weirs varied from eight in 1996 to 312 in 2001. Of the 390 animals released with a numbered identification tag, 25 were recaptured in weirs and 4 of those porpoises entered a weir a third time. Males comprised 63.5% of entrapments. Weirs and demersal gillnets captured animals from the same population, but the weir bycatch was biased towards younger, smaller animals. Porpoises that became trapped in weirs exhibited measures of body condition similar to those killed in gillnets and by gunshot wounds in the same waters. None were considered emaciated. Mortality in weirs appeared to be random; porpoises that died during release attempts were of the same age and sex composition and body condition as the individuals that survived. The use of a specialised large-mesh seine significantly increased the probability of successful release. Observations of the stomach contents data of porpoises killed in weirs indicate that porpoises feed while trapped in weirs, but perhaps not at the same rate as animals killed in gillnets. Entrapments peaked in August, concurrent with the highest landings of Atlantic herring, the target species of the weir fishery. Based on a logistical regression model, porpoises are 3.3 times more likely to swim into a weir on a night in which high tide falls during darkness. Weir entrapments do not have a significant effect on this population, largely because of on-going efforts to release porpoises from weirs.
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R. Eslinger, Kam, and Brian M. Crookston. "Energy Dissipation of Type a Piano Key Weirs." Water 12, no. 5 (April 28, 2020): 1253. http://dx.doi.org/10.3390/w12051253.
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A Piano Key weir (PK weir) is a nonlinear, labyrinth-type weir well suited for rehabilitation projects due to a relatively small footprint and the ability to pass large discharges for lesser upstream-head values when compared with other weir types. A critical component of a hydraulic structure is the energy-dissipative properties. Currently, information and guidance is limited, with previous energy dissipation studies of PK weirs primarily of specific projects. Therefore, to document and quantify energy dissipation, four laboratory-scale Type A PK weir models with different width ratios (Wi/Wo) were studied, with 255 tests comprising this new dataset, along with detailed observations of the flow field. Results were compared to existing published data regarding energy dissipation downstream of trapezoidal and rectangular labyrinth weirs. To support design efforts, two equations, both functions of head-water ratio (H/P) and Wi/Wo, are proposed to predict the relative residual energy downstream of PK weirs. The energy dissipation of PK weirs is largest at low flows and decreases in a logarithmic-like manner as flow increases. PK weirs with increased hydraulic efficiency, caused by an increase in Wi/Wo, resulted in slightly smaller energy dissipation values within the range 0.2 ≤ H/P ≤ 0.8. The energy dissipation of PK weirs was found to be relatively constant, independent of Wi/Wo, and in the ranges 0.07 ≤ H/P ≤ 0.2 and 0.8 ≤ H/P ≤ 0.95.
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Mohammed, Rangeen Shihab, and Shaker Abdulatif Jalil. "Hydraulic Performance of Sharp-Crested Labyrinth Weir." Academic Journal of Nawroz University 11, no. 1 (February 7, 2022): 47–56. http://dx.doi.org/10.25007/ajnu.v11n1a1025.
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Weirs are used as a control structure in the waterways. Among the influencing geometrical parameters on the weir performance is the total crest length. Experimental work on 27 geometric models of two-cycle Labyrinth shape crest weir is tested. The tested physical models consist of three weir heights, three apex widths and the sidewall angle is between (4.67°≤ α ≤ 19°), with three models of rectangular labyrinth weirs. The weirs of the wider apex and the same total length perform better and its coefficient of discharge is higher. Labyrinth weirs of longer sidewall length and contents same apex width performance batter. The larger value of sidewall angle and for a constant apex width reduces the value of discharge coefficient. The value of Cd range from (0.34-0.83) for the ratio of upstream head to the weir height (h/P) is ranged (0.08-0.48). The equations to predict the value of the discharge coefficient are suggested within the limitations of the present study.
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Alizadeh Sanami, Forough, Amir Ghaderi, Fardin Alizadeh Sanami, Parisa Mirkhorli, and Silvia Di Francesco. "Laboratory Study of the Hydraulic Performance of the A-Type Triangular Piano Key Weir." Water 15, no. 11 (June 2, 2023): 2124. http://dx.doi.org/10.3390/w15112124.
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A piano key weir (PKW), a new type of weir aiming to increase the discharge capacity of an existing dam, was recently designed. Despite a large body of research in this field, only a few studies were conducted on A-type triangular piano key weirs (TPKW) in straight channels. In this context, this present research sought to study the flow regime, stage–discharge relationship, and discharge coefficient. Experiments were carried out using nine TPKW models and three linear weirs (LW) as the control weirs. The results indicated that the triangular piano key weirs are capable of passing a higher discharge in similar laboratory conditions compared to linear key weirs due to their longer length. For a given h/P ratio (h is the water head over the weir crest, and P is the weir height) and constant length (Le), an increase in the weir height from 0.07 m to 0.15 m decreases the discharge coefficient by approximately 20%. From sensitivity analysis, the most influential parameters for the tested TPKW models are the h/Le dimensionless ratio, followed by the P/Le and Fr. Moreover, the discharge coefficient has a reverse trend when the dimensionless parameters h/P, h/Le, and Froude number are increased. However, with decreasing h/Le, the discharge coefficient of TPKW tends to that of a broad-crested weir because of local submergence. It is expected that the results obtained will be a reference for researchers who work in this field.
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Baylar, Ahmet, Tamer Bagatur, and Ahmet Tuna. "Aeration Performance of Triangular Notch Weirs at Recirculating System." Water Quality Research Journal 36, no. 1 (February 1, 2001): 121–32. http://dx.doi.org/10.2166/wqrj.2001.008.
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Abstract An adequate supply of dissolved oxygen is essential for the survival of aquatic organisms. Hydraulic structures can increase dissolved oxygen levels by creating turbulent conditions, where small air bubbles are carried into the bulk of the flow. Plunging overfall jets from weirs at recirculating systems are a particular instance of this. This paper seeks triangular notch weirs having different weir angle (α) and how they affect the aeration performance. It is demonstrated that the aeration efficiency of a 90° triangular notch weir is generally better than that of the other weirs.
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Roushangar, Kiyoumars, Mohammad Taghi Alami, Jalal Shiri, and Mahdi Majedi Asl. "Determining discharge coefficient of labyrinth and arced labyrinth weirs using support vector machine." Hydrology Research 49, no. 3 (March 3, 2017): 924–38. http://dx.doi.org/10.2166/nh.2017.214.
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Abstract A labyrinth weir is a linear weir folded in plan-view which increases the crest length and the flow rate for a given channel width and an upstream flow depth. The present study aimed at determining discharge coefficients of labyrinth and arced labyrinth weirs using support vector machine (SVM)-based models. A total of 527 laboratory test data of four types of weirs, namely, Normal and Inverted orientation Labyrinth Weirs in flume (NLW, ILW) and Arced Labyrinth Weirs with and without nappe Breakers in reservoir (ALW, ALWB), were captured from the published literature and utilized to feed the SVM-based models. The obtained results revealed the capability of the SVM-based models in determining discharge coefficients. The results showed that the SVM-based model of arced labyrinth weir (ALW) produced the most accurate results when three dimensionless parameters, e.g. (HT/P) head water ratio, (α/θ) angle ratio and (Lc/W) magnification ratio, were introduced as input parameters (Root mean square error [RMSE]= 0.013 and R2 = 0.970 for the test stage). Nonetheless, sensitivity analysis showed that Froude number and head water ratio are the most influential parameters on discharge coefficients of the labyrinth and arced labyrinth weirs, respectively.
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Rdhaiwi, Ali Qasim, Ali Khoshfetrat, and Amirhossein Fathi. "EXPERIMENTAL COMPARISON OF FLOW ENERGY LOSS IN TYPE-B AND -C TRAPEZOIDAL PIANO KEY WEIRS (PKWS)." Journal of Engineering and Sustainable Development 28, no. 1 (January 1, 2024): 55–63. http://dx.doi.org/10.31272/jeasd.28.1.4.
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As non-linear weirs with a high flow rate, Piano Key Weirs (PKWs) have attracted the attention of water engineers in recent years. Given the limited information available on the energy losses of these weirs, it is important to investigate the energy losses and discharge capacity of these weirs. In this research, two trapezoidal PKWs, i.e., type-B and -C, with a height of 0.2 m were used. The studied flow rates were 0.025, 0.03, 0.035, and 0.04 m3/s. The results showed that energy loss decreased by increasing the flow velocity and upstream depth. The average energy loss in the type-B trapezoidal PKW was about 10.9% lower than that in the type-C PKW. The type-B weir had a higher discharge coefficient of about 5.6% compared to that of the type-C weir. Finally, an equation was presented to calculate the energy loss of these two weirs with a correlation coefficient of 97.42%.
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Namaee, Mohammad Reza, Mohammad Sadegh Jalaledini, Mahdi Habibi, Saeed Reza Sabbagh Yazdi, and Mona Ghafouri Azar. "Discharge coefficient of a broad crested side weir in an earthen channel." Water Supply 13, no. 1 (February 1, 2013): 166–77. http://dx.doi.org/10.2166/ws.2012.081.
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Side weirs are widely used to divert flows from rivers and channels. However, the hydraulic behavior of this type of weir is complex and difficult to predict accurately. Previous studies on side weirs have generally focused on side weirs in rectangular channels with a smooth bed. However, one of the applications of side weirs is in irrigation systems which have trapezoidal cross sections and significant bed roughness. The present study investigates the hydraulic behavior of a broad crested side weir in an earthen channel with a rough bed under subcritical flow. These investigations showed that the side weir discharge coefficient is influenced by four main parameters which are upstream Froude number, ratio of the main channel width to the upstream flow depth, ratio of the length of the side weir to the main channel width and ratio of side weir height to the upstream flow depth. The results showed that the discharge coefficient of the side weir gives a lower coefficient value compared to other researchers’ equations. Nearly 90 experimental tests were carried out and finally new equations are proposed for prediction of discharge coefficient of a broad crested side weir in an earthen channel under subcritical conditions which can be mainly used in common irrigation systems.
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Pařílková, Jana, Jaromír Říha, and Zbyněk Zachoval. "The Influence of Roughness on the Discharge Coefficient of a Broad-Crested Weir." Journal of Hydrology and Hydromechanics 60, no. 2 (June 1, 2012): 101–14. http://dx.doi.org/10.2478/v10098-012-0009-0.
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The Influence of Roughness on the Discharge Coefficient of a Broad-Crested Weir The use of environmentally-friendly materials in hydraulic engineering (e.g. the stone lining of weirs at levees) calls for the more accurate estimation of the discharge coefficient for broad-crested weirs with a rough crest surface. However, in the available literature sources the discharge coefficient of broad-crested weirs is usually expressed for a smooth crest. The authors of this paper have summarized the theoretical knowledge related to the effect of weir crest surface roughness on the discharge coefficient. The method of determination of the head-discharge relation for broad-crested weirs with a rough crest surface is proposed based on known discharge coefficient values for smooth surfaces and on the roughness parameters of the weir. For selected scenarios the theoretical results were compared with experimental research carried out at the Laboratory of Water Management Research, Faculty of Civil Engineering (FCE), Brno University of Technology (BUT).
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Qasim Rdhaiwi, Ali, Ali Khoshfetrat, and Amirhossein Fathi. "EXPERIMENTAL INVESTIGATION OF SCOUR DOWNSTREAM OF A C-TYPE TRAPEZOIDAL PIANO KEY WEIR WITH STILLING BASIN." Journal of Engineering and Sustainable Development 27, no. 6 (November 1, 2023): 688–97. http://dx.doi.org/10.31272/jeasd.27.6.2.
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In recent years, engineers have focused on finding a solution to reduce scouring downstream of piano key weirs. Piano key weirs have high efficiency in flood flow and a higher discharge coefficient. In this research, a type C trapezoidal piano key weir with a type 1 stilling basin was used. Three discharges and three water depths were also used. The results showed that the existence of the stilling basin reduces scour. In the weir with the stilling basin, the maximum scour depth is reduced and the scouring hole becomes more elongated. The maximum distance of the scouring depth increases compared to the toe of the weir. The maximum scour depth and the maximum scour depth distance in the weirs with the stilling basin are about 63.4% less and 20.4% more, respectively than in the weirs without the stilling basin. Additionally, by increasing the flow rate and decreasing the depth of the downstream flow, the amount of scour increases.
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Gunjalli, Gowthami, Aishwarya S, Muthu D, Venkata Subramaniam C, and Ramakrishnan K. "Perforated Weir for Effective Operation – A Study." International Journal of Engineering & Technology 7, no. 3.12 (July 20, 2018): 285. http://dx.doi.org/10.14419/ijet.v7i3.12.16043.
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The excess water during monsoon season in the river is retained using low dams and it overflows through weirs. Maintaining the water depth at the required level and increasing the discharge from the weir are the current problems facing now a days. To overcome these problems, a novel sharp crested perforated weir has been developed in this work with different shapes of perforations viz. circle, rectangle, square and triangle having same area of perforation. A total of 24 models were made with single, double, triple opening for each shape, under two different sets of area of openings. The models were examined in a hydraulic tilting flume by keeping the discharge as constant. The variation in head obtained from these perforated weirs for different shapes were compared with a control weir which is a sharp crested rectangular weir. The expected theoretical discharge from these perforated weirs is compared with the actual discharge obtained. The values of coefficient of discharge for different perforated weirs were obtained by minimizing the error and the effective perforated weir is arrived by analyzing the values. This solution can be applied in solving practical problems.
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Hussain, Rukaia A., and Sahar A. Mohammed. "Discharge Coefficient for Cylindrical Weirs." Tikrit Journal of Engineering Sciences 13, no. 1 (March 31, 2006): 82–96. http://dx.doi.org/10.25130/tjes.13.1.05.
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The hydraulic characteristics of cylindrical weirs under free flow conditions were studied experimentally in order to investigate the discharge coefficient (Cd) and the influence of some significant factors and performance of weirs for discharge measuring. The experimental tests were carried out on three models of weirs in which the diameter of weir (D) was varied three times as: 8.0, 10.0 and 12.0 cm. For each model, a series of measurements were taken to measure coefficients of discharge. Results showed that the coefficient of discharge (Cd) increase with increasing the ratio of head to weir diameter (h/D),and for the same ratio (h/D), the discharge coefficient (Cd) increases with increasing weir diameter.
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Baylar, Ahmet, and M. Emin Emiroglu. "The effect of sharp-crested weir shape on air entrainment." Canadian Journal of Civil Engineering 29, no. 3 (June 1, 2002): 375–83. http://dx.doi.org/10.1139/l02-017.
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Aeration in the waters of rivers and streams is very important to the quality and existence of aquatic life. If the overfall jets downstream of weir structures plunges into a plunge pool, entrained air bubbles will contribute to aeration. This paper investigates sharp-crested weirs having different cross-sectional geometry and their effect on the air entrainment rate. It is demonstrated that the air entrainment rate of a 30° triangular sharp-crested weir is better than that of the other sharp-crested weirs tested. Moreover, variation in the number of V-notches over the width of the weir plate was studied for 30° triangular sharp-crested weirs. The 30° triangular sharp-crested weir with two V-notches was found to have higher values of air entrainment rate.Key words: aeration, air entrainment rate, plunging overfall jet, sharp-crested weir.
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Bhukya, Raj Kumar, Manish Pandey, Manousos Valyrakis, and Panagiotis Michalis. "Discharge Estimation over Piano Key Weirs: A Review of Recent Developments." Water 14, no. 19 (September 26, 2022): 3029. http://dx.doi.org/10.3390/w14193029.
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The piano key (PK) weir has advanced over the labyrinth weir to increase the discharge capacity. Piano key weirs exhibit nonlinear flow behavior and are easy to place on the existing spillway or newly constructed dam with less base area. Various investigators are given equations to calculate the discharge coefficient for free and submerged flow conditions. The study focuses on reviewing the impacts of the PK weir geometry on the weir flow discharge coefficient, including weir length and height, upstream and downstream key widths, and apex overhangs. In this study, all possible aspects of PK weirs were briefly reviewed. From sensitivity analysis, it is observed that the discharge coefficient of the PK weir is more sensitive for the L/W dimensionless ratio followed by the B/P ratio. L is total length of the weir crest, W is width of the weir, B is total width of PK weir and P is height of the weir. This review paper is intended to serve as an accessible resource for hydraulic structures researchers and hydraulic engineering professionals alike interested in the hydraulics of PK weirs.
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Guan, Dawei, Jingang Liu, Yee-Meng Chiew, and Yingzheng Zhou. "Scour Evolution Downstream of Submerged Weirs in Clear Water Scour Conditions." Water 11, no. 9 (August 22, 2019): 1746. http://dx.doi.org/10.3390/w11091746.
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Although weirs or dikes in the riverine and coastal environments are frequently overtopped, few studies have hitherto examined the evolution of the scour process downstream of these structures under the submerged condition. This paper presents an experimental investigation on time evolution of the scour process downstream of submerged weirs with a uniform coarse sand. The clear-water scour experiments were carried out in a tilting recirculation flume. Different flow intensities and overtopping ratios (approach flow depth/weir height) were adopted in the experiments. Experimental observations show that the scour hole downstream of submerged weirs develops very fast in the initial stage, before progressing at a decreasing rate and eventually reaching the equilibrium stage. The results show that an increase of the overtopping ratio or flowrate can generate larger scour depth and volume downstream of the weir. Moreover, geometrical similarity of the scour hole that formed downstream of the weir was observed in the tests. Finally, empirical equations for predicting scour hole geometrical evolutions downstream of the submerged weirs were presented. The results of this study are useful in the development of numerical/analytical models capable of estimating the scour depth downstream of weirs in the river or coastal areas, for which the overtopping conditions are present.
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Bijankhan, Mohammad, and Vito Ferro. "Dimensional analysis and stage-discharge relationship for weirs: a review." Journal of Agricultural Engineering 48, no. 1 (February 17, 2017): 1–11. http://dx.doi.org/10.4081/jae.2017.575.
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Deducing the weir flow stage-discharge relationship is a classical hydraulic problem. In this regard Buckingham’s theorem of dimensional analysis can be used to find simple and accurate formulas to obtain the rating curves of different weir types. At first, in this review paper the rectangular weir that is a very common hydraulic structure is studied. It is indicated that the crest shape, approach channel width, obliquity (angle between the weir crest and the direction normal to the flow motion) and vertical inclination (pivot weir) are the key-parameters affecting the flow over the rectangular weirs. The flow over the triangular, labyrinth, parabolic, circular, elliptical, and W-weirs are also studied using dimensional analysis and incomplete self-similarity concept. For all mentioned weirs the stage-discharge relationships are presented and the application limits are discussed. The results of this paper can be used and implemented by the irrigation and drainage network designers to simplify the procedure of weir design.
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Bettez, J., R. D. Townsend, and A. Comeau. "Scale model testing and calibration of City of Ottawa sewer weirs." Canadian Journal of Civil Engineering 28, no. 4 (August 1, 2001): 627–39. http://dx.doi.org/10.1139/l01-024.
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This paper reports the results of a laboratory study of the effects of (i) manhole proximity to installation site, (ii) pipe slope (i.e., approach velocity), (iii) upstream head measurement location, and (iv) submergence on the "hydraulics" of two types of sewer weirs used by the City of Ottawa. The City's streamlined form of broad-crested weir and its compound-shaped sharp-crested weir were initially calibrated for a "pipe straight"-arrangement (no upstream manhole is present) for a wide range of flow conditions at 0.2%, 0.4%, and 1.0% pipe slopes. The calibration tests were then repeated with the weirs positioned immediately downstream of a model manhole structure ("manhole"-arrangement). Corresponding data sets were compared to determine the effects of (i) approach velocity and (ii) manhole proximity (for two different shapes of manhole "benching") on the respective weir discharge coefficients.Key words: sewer weirs, broad-crested weir, compound sharp-crested weir, calibration, sewer benching, discharge coefficients.
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Kipnusu, Evagzard Korir, Charles Mwithali M´Erimba, and John Gichimu Mbaka. "Impact of Weirs on Decomposition Rates of Dombeya goetzenii (K. Schum) Leaf Litter in the River Njoro, Kenya." African Journal of Pure and Applied Sciences 4, no. 3 (December 30, 2023): 1–11. http://dx.doi.org/10.33886/ajpas.v4i3.424.
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Water storage impoundments have deleterious effects on the structure and functioning of running water ecosystems. Many studies have been undertaken on the impacts of large impoundments on river ecosystems. However, comparatively few researches have determined the impact of small weirs on the functioning and structure of running water ecosystems. The main objective of the current study was to determine the impact of weirs on the decomposition rates of Dombeya goetzenii leaf litter in the Njoro River. The study was undertaken at five study sites located along the middle reaches of the Njoro River, near Egerton University, between November 2021 and January 2022. Four study sites were situated at upstream and downstream areas (i.e., approximately 10 m) of two weirs (i.e., Treetops and Canning weirs). A reference site was situated approximately 100 m upstream from the impoundment of the first weir. Physicochemical factors such as temperature, conductivity and nutrients (e.g., nitrates, ammonium) were determined at each study site. Additionally, decomposition rates of one of the most common tree species (i.e., Dombeya goetzenii) found growing along the Njoro River were determined. Leaf litter decomposition was determined using fine (100 µm) and coarse (500 µm) mesh litter bags and the negative exponential decay model was used to estimate decomposition rates (-k per day). The mean leaf litter decomposition rate was highest at the reference site (-k/day = 0.04) and lowest (-k/day = 0.02) at the upstream side of the first weir (i.e., Treetops weir).Leaf litter decomposition rates differed significantly (p = 0.002) between the aforementioned sites. Weirs had a significant local effect on the decomposition rates of Dombeya goetzenii leaf litter. The study provides crucial information to managers of riverine ecosystems about the impact of water storage weirs on an ecosystem function. The concerned government agencies should take action to prevent negative effects of weirs on riverine ecosystems.
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Al Babely, Emad Abdul-Gabbar, Adnan Abdul-Wahab Al Muhammad, and Mohammad A. Al Dabbagh. "Overflow Characteristic of Cylindrical Shape Crest Weirs over Horizontal Bed." Tikrit Journal of Engineering Sciences 18, no. 4 (December 31, 2011): 29–39. http://dx.doi.org/10.25130/tjes.18.4.04.
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The most common types of weirs are the broad-crested weir, the sharp-crested weir, the circular crested weir and the ogee crested weir. Advantages of the cylindrical weir shape include the stable overflow pattern, the ease to pass floating debris, the simplicity of design compared to ogee crest design and the associated lower costs. In present study, it was investigated the overflow characteristics of circular weirs in laboratory for various cylinder radii of three sizes (11.4, 9.0, 6.3 cm), and the models fixed on the channel bed vertically to the direction of flow. The result shows that the increase in the ratio of head to weir radius ratio (Hw/R) value causes an increase in discharge coefficient (Cd) value for the same height of weir. It was observed that the cylinder size (i.e. radius of cylindrical weir (R)) has an effect on the (Cd). The flow magnification factor (qw/qs) increases with an increase in (Hw/R) value and values of (qw/qs) were always higher than one for all values of (Hw/R), this means that weirs of cylindrical shape performed better than those of sharp crest for any value of weir radius tested in this study
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Rajaratnam, N., C. Katopodis, and M. A. Fairbairn. "Hydraulics of culvert fishways V: Alberta fish weirs and baffles." Canadian Journal of Civil Engineering 17, no. 6 (December 1, 1990): 1015–21. http://dx.doi.org/10.1139/l90-112.
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This paper presents the results of a laboratory study of the hydraulic performance of fish weirs and fish baffles used by Alberta Transportation for improving the fish-passing capacity of culverts. It was found that if the longitudinal spacing of the weirs is limited to 0.6 and 1.2 times the diameter of the culvert, their performance is comparable to that of the corresponding weir and slotted-weir baffle systems, with regard to the depth of pool between the baffles as well as the barrier velocity. On the other hand, the fish baffles did not perform as well as the fish weirs under the conditions tested. Key words: culverts, fishways, baffles, turbulent flow, hydraulics, open-channel flow.
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Pirzad, M., M. H. Pourmohammadi, H. Ghorbanizadeh Kharazi, M. Solimani Babarsad, and E. Derikvand. "Experimental study on flow over arced-plan porous weirs." Water Supply 22, no. 3 (December 23, 2021): 2659–72. http://dx.doi.org/10.2166/ws.2021.446.
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Abstract Unlike conventional impermeable weirs, porous weirs do not clog the flow and passage of aquatic life with increased aeration or aerobic reactions. They have minimal negative effects on the environment and are known as environmentally friendly structures. This study experimentally investigates the hydraulic performance of arced-plan porous weirs (APPWs) in different hydraulic and geometric conditions. For this purpose, four different porous and two solid weirs were examined. Experiments were conducted in a horizontal laboratory flume with length, width and height of 20, 0.6 and 0.5 m, respectively, for a wide range of flow rates, particle sizes and three arc lengths. Results showed that increasing filling material sizes increases the free discharge coefficient and reduces the submerged discharge reduction factor (DRF). It was also concluded that the weirs’ effective length significantly impacts the free discharge coefficient and has no significant effect on the threshold submergence index and submerged DRF. Unlike solid weirs, the threshold submergence of porous weirs occurs at a downstream depth lower than the weir's height. Finally, according to the dimensional analysis and gene-expression programming approach, three relations were extracted to calculate the free discharge coefficient, threshold submergence index and submerged DRF for APPWs.
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Wibowo, A. R., M. Bisri, Sumiadi, and V. Dermawan. "Model of discharge coefficient of crest gate rubber weir at fully closed condition." IOP Conference Series: Earth and Environmental Science 930, no. 1 (December 1, 2021): 012026. http://dx.doi.org/10.1088/1755-1315/930/1/012026.
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Abstract Crest Gate Rubber Weir is a modification of rubber weir with adding a metal plate or crest gate on the upstream side. The rubber in this weir functioning as a support while the crest gate serves on elevating water. Although many have been implemented, this weir’s discharge coefficient needs be researched considering its unique shape. This study looks for discharge coefficient to determine the discharge that passes through weirs at fully closed conditions. The research was conducted with a hydraulic model resembling part of Tirtonadi Weir in Surakarta with a hydraulic model. The model is made in an angle 53°, which represents the prototype at fully closed condition. Laboratory experiment shows that the discharge coefficient of this weir is greater than the Ogee Weir and Sluice Gate for the same height because of less flow resistance from this weir structural form.
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Valentine, Elizabeth, Kurt Kronebusch, David Z. Zhu, N. Rajaratnam, Sid Lodewyk, John Cairns, Steven Chan, and Fayi Zhou. "Combined sewer overflow over an oblique weir at Rat Creek in Edmonton, Alberta." Canadian Journal of Civil Engineering 37, no. 3 (March 2010): 477–88. http://dx.doi.org/10.1139/l09-177.
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Oblique weirs are commonly used in urban drainage systems to remove excess flow from a sewer, in particular, a combined sewer system that has limited conveyance capacity. It is important to understand the hydraulics of these weirs to properly monitor the amount of the overflows as well as to design and improve sewer systems. The Rat Creek structure in Edmonton, Alberta, is a combined sewer overflow structure with a weir at an oblique alignment to the centerline of the sewer. A physical model study of the structure was conducted. The results show that both the approach flow conditions and the chamber geometry can significantly affect the hydraulic performance of the weir and invalidate the application of standard weir equations. A unique flow regime with a linear head–discharge rating curve was observed. The effects of modifying the weir and the hanging baffle wall downstream of the weir were also studied and reported. The results of this case study help to improve the understanding of the hydraulics of oblique weirs in sewer systems.
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Sanz-Ronda, Francisco Javier, Francisco Javier Bravo-Córdoba, Ana García-Vega, Jorge Valbuena-Castro, Andrés Martínez-de-Azagra, and Juan Francisco Fuentes-Pérez. "Fish Upstream Passage through Gauging Stations: Experiences with Iberian Barbel in Flat-V Weirs." Fishes 6, no. 4 (December 14, 2021): 81. http://dx.doi.org/10.3390/fishes6040081.
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The monitoring of river discharge is vital for the correct management of water resources. Flat-V gauging weirs are facilities used worldwide for measuring discharge. These structures consist of a small weir with a triangular cross-section and a flat “V”-shaped notch. Their extensive use is a consequence of their utility in the measurement of both low and high flow conditions. However, depending on their size, local morphology and river discharge can act as full or partial hydraulic barriers to fish migration. To address this concern, the present work studies fish passage performance over flat-V weirs considering their hydraulic performance. For this, radio-tracking and video-monitoring observations were combined with computational fluid dynamics (CFD) models in two flat-V weirs, using Iberian barbel (Luciobarbus bocagei) as the target species. Results showed that fish passage is conditioned by both hydraulic and behavioral processes, providing evidence for scenarios in which flat-V weirs may act as full or partial barriers to upstream movements. For the studied flat-V weirs, a discharge range of 0.27–8 m3/s, with a water drop difference between upstream and downstream water levels lower than 0.7 m and a depth downstream of the weir of higher than 0.3 m can be considered an effective passage situation for barbels. These findings are of interest for quantifying flat-V weir impacts, for engineering applications and for establishing managing or retrofitting actions when required.
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Kim, Young-Hyo, In-Hwan Cho, Ha-Kyung Kim, Eun-A. Hwang, Byung-Hun Han, and Baik-Ho Kim. "Assessing the Impact of Weirs on Water Quality and Phytoplankton Dynamics in the South Han River: A Two-Year Study." Water 16, no. 6 (March 13, 2024): 833. http://dx.doi.org/10.3390/w16060833.
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This study investigates the ecological effects of weirs on water quality and phytoplankton communities in the South Han River (SHR) over a two-year period. By focusing on three key weirs—Kangcheon Weir, Yeoju Weir, and Ipo Weir—the research examines how artificial structures influence river hydrodynamics, nutrient cycles, and algal growth patterns. Utilizing water quality measurements, phytoplankton analysis, and environmental factor assessments, the study identifies significant fluctuations in water quality parameters and phytoplankton abundance across the surveyed points. The analysis reveals a direct correlation between environmental conditions such as temperature, flow rates, and nutrient concentrations, particularly nitrogen and phosphorus, and the proliferation of harmful cyanobacteria, notably Microcystis. This research highlights the critical role of comprehensive management strategies that consider hydraulic residence time, nutrient balance, and temperature regulation to mitigate the impacts of weirs on river ecosystems and improve water quality in the SHR.
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Hadi, Zahraa Muslim, and Hayder Q. Majeed. "Simulation of the Entrance to the Escape of the Flood Branching from the Diyala River." Journal of Engineering 29, no. 08 (August 1, 2023): 138–48. http://dx.doi.org/10.31026/j.eng.2023.08.10.
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The Diyala River is considered the third most important river in Iraq. However, in the recent period, Diyala Governorate has been subject to several floods. This study aims to simulate an efficient labyrinth weir at the flood escape entrance branching from the Diyala River to reach the best entrance through which the flood waves can pass safely. The discharge coefficient was calculated laboratory for five types of trapezoidal side labyrinth weirs with different sidewall angles. Results showed that the coefficient discharge for the trapezoidal labyrinth side weir with an angle of the sidewall is 75ᵒ and has a discharge coefficient greater than the rest of the labyrinth side weirs. The second part of this study is validating the laboratory work using the CFD technique, where the same laboratory channel was simulated with the weirs of the side trapezoidal labyrinth using the Ansys-Fluent program. The numerical study gave very close results compared with the experimental results with MSE, where the error percentage error was from 3.3% to 10%. The last part of the work is numerically simulating the trapezoidal labyrinth side weir with an angle of the sidewall of 75ᵒ at the flood escape entrance branching from the Diyala River. The results showed that the side labyrinth weir has a larger discharge capacity of 4.8% than the rest of the traditional weirs and is more effective in flood treatment.
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Hubble, T. C. T. "Slope stability analysis of potential bank failure as a result of toe erosion on weir-impounded lakes: an example from the Nepean River, New South Wales, Australia." Marine and Freshwater Research 55, no. 1 (2004): 57. http://dx.doi.org/10.1071/mf03003.
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The consequences of weirs present on the Upper Nepean River on the long-term slope stability of both vegetated and devegetated riverbanks were investigated using models that account for the reinforcement of bank sediments by tree roots. The effects of the weirs in concert with channel widening and deepening caused by dredging in 1970s and 1980s, as well as natural processes, have turned the Upper Nepean from a small upland river into a series of quiet, narrow lakes, measuring 3–5 m deep, 30–70 m wide and several kilometres long. The surface of these lakes is located currently within the steep mid-bank zone. Wind-generated waves have eroded 1–3-m high scarps in the mid-bank region. These scarps are receding laterally at an average rate of 10 cm per year and this process is gradually undermining and destabilising the upper banks. In contrast, the mass of water impounded by the weirs currently acts to provide lateral support to the banks and improves their stability. Therefore, the existence of the weirs and their impounded lakes has currently both positive and negative effects on bank stability. The retention of the weirs will promote continued erosion at the waterline of the weir lakes that will eventually lead to the destabilisation and collapse of both vegetated and devegetated banks during future large floods. Demolition of the weirs would also lead to a renewed phase of bank failure during future floods as the stabilising effects of the weir lakes on the banks would be removed. The size of eventual failures will be larger and the distribution of such failures probably more widespread if the weirs are retained.
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Ghadba, Edan I. "Hydraulic Characteristics of Semi- Circular Sharp Crested Weirs." Tikrit Journal of Engineering Sciences 18, no. 1 (March 31, 2011): 58–68. http://dx.doi.org/10.25130/tjes.18.1.11.
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In this research the hydraulic characteristics of sharp crested weirs with semi- circular shape were studied, the study was depended on the dimensional analysis which confirmed by experimental work. The dimensional analysis results demonstrate that the effective parameters on the discharge of flow over this type of weir are the ratio of water height above the weir crest to the radius of this weir (H/R) and the ratio of water height above the weir crest to the height of the crest (H/P). Experimental tests were carried out on (16) models of weirs with Semi-circle shape where the radius of cutting was change four times (R=5, 10, 15, 20 cm) and for any radius the height of the crest was change four times (P= 30, 25, 20, 15 cm). The results show a great influence of the parameter (H/R) on flow parameter (Q2/gH5) while the effect of the parameter (H/P) is limited. Depending on non-dimensional parameters and experimental results, the statistics program (SPSS) were used to create empirical equation for measuring the discharge over the sharp crested weirs with semi-circular shape. The results of the equation show a very good agreement with the experimental result for determine the discharge with knowing the depth of water over the weir (H) , radius of cutting of the weir (R) and height of the crest (P). Also the equation shows a great influence of the radius (R) and limited influence of the height (P) on the discharge over this type of weirs.
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Lindermuth, Adrian, Théo St Pierre Ostrander, Stefan Achleitner, Bernhard Gems, and Markus Aufleger. "Discharge Calculation of Side Weirs with Several Weir Fields Considering the Undisturbed Normal Flow Depth in the Channel." Water 13, no. 13 (June 22, 2021): 1717. http://dx.doi.org/10.3390/w13131717.
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Discharge behavior at side weirs is significantly influenced by the water surface profile along the weir crest. In the past century, different approaches were developed to describe this profile and the associated discharge coefficients. However, the application of these methods to practical problems poses a particular challenge, as a complex three-dimensional funnel is formed due to the discharge reduction, leading to significant uncertainties in determining the relevant flow depth. For this reason, a new approach for the determination of the discharge coefficient of side weirs was developed that refers to the undisturbed normal flow depth in the main channel. Based on a comprehensive parametric study utilizing 3D-numerical simulations, the influence of the weir and channel characteristics on the discharge behavior at the side weir was analyzed. A revised formula for estimating the discharge coefficient for side weirs with multiple weir fields was derived using multiple regression analyses. Validation of the numerical simulations was carried out by applying a physical scale model, showing good agreement between the results.
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Wang, Yue, Jihong Xia, Wangwei Cai, Zewen Liu, Jingjiang Li, Jingyun Yin, Jiayi Zu, and Chuanbin Dou. "Response of Fish Habitat Quality to Weir Distribution Change in Mountainous River Based on the Two-Dimensional Habitat Suitability Model." Sustainability 15, no. 11 (May 27, 2023): 8698. http://dx.doi.org/10.3390/su15118698.
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Weirs are often constructed on mountainous rivers because of their low construction costs and their ability to provide irrigation and facilitate landscaping, yet there is little research on how fish habitat quality in mountainous rivers responds to weir distribution. This study categorized the distribution characteristics of weirs on typical reaches according to their sinuosity and calculated the corresponding habitat suitability index (HSI) and weighted usable area (WUA) under various discharge conditions using a coupled MIKE21 and habitat suitability model. Then, the relationship between the distribution characteristics of weirs and the quality of fish habitats under different discharge conditions was analyzed. The results show that weirs in mountainous rivers can affect the habitat suitability of the rivers, but this effect is closely related to discharge conditions and layout mainly because the key hydraulic factors that determine habitat quality for different sinuous reaches vary under different discharge conditions. This study found that in high-sinuosity rivers with high discharge conditions, water depth is the key factor determining the quality of fish habitats, so weirs can improve habitat quality by improving the suitability of downstream water depth. However, in other conditions, velocity is the key factor determining habitat quality, in which case weirs cannot improve habitat quality and can even degrade it. Therefore, other methods of improving velocity are needed to enhance habitat quality. The results of this study provide a reference for the protection of fish habitats in mountainous river channels and the determination of suitable locations for weir construction.
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Kabwe, Alex Lushikanda, Masahiro Hyodo, Hidehiko Ogata, Yoshihiro Sagawa, Yoshinao Adachi, and Masayuki Ishii. "The Factors Affecting Stability and Durability of Flow Diversion Simple Weirs in Muchinga Province of Zambia." Water 16, no. 13 (June 28, 2024): 1852. http://dx.doi.org/10.3390/w16131852.
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The effectiveness of simple weirs and the ability of rural farmers to construct durable weirs are still areas of concern in rural areas in Zambia. The objective of this study is to investigate the factors contributing to the varying levels of durability of the simple weir structures used for the diversion of river flows. This study was conducted in five districts where 33 simple weirs located in similar geographical zones were analyzed for their longevity. The research delved into catchment and climatic variables, as well as the social and psychological perception of simple weirs. This study conducted interviews with key informants who were familiar with the use of simple weirs in Muchinga Provinces between 26 December 2023 and 15 January 2024 using semi-structured questions. The findings of this study indicated that simple weirs constructed on relatively square-shaped catchments and narrow-shaped catchment areas were less vulnerable to damage and easy to operate and maintain. The study also found that climatic factors such as storm rainfall events had little impact on the operation and maintenance of these weirs in Muchinga province, as most sites are in the rainfall shadow while farmers’ views about the structures varied from site to site. Overall, planning is necessary for implementing small or large irrigation structures.
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Azimi, Hamed, and Saeid Shabanlou. "Comparison of Subcritical and Supercritical Flow Patterns Within Triangular Channels Along the Side Weir." International Journal of Nonlinear Sciences and Numerical Simulation 17, no. 7-8 (December 1, 2016): 361–68. http://dx.doi.org/10.1515/ijnsns-2015-0103.
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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.
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Baylar, Ahmet. "An Investigation on the Use of Venturi Weirs as an Aerator." Water Quality Research Journal 38, no. 4 (November 1, 2003): 753–67. http://dx.doi.org/10.2166/wqrj.2003.047.
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Abstract The most classic example of a hydraulic structure where gas transfer occurs is a weir. Transfer of gases between the atmosphere and river water can occur in a free overfall jet from a weir. A free overfall jet from a weir plunging into downstream water causes entrainment of air bubbles if the free overfall jet velocity exceeds the critical value where aeration occurs. This paper investigates the free overfall jets from Venturi and rectangular notch weirs and their effect on air entrainment rate. A Venturi weir was placed at the upstream channel end in order to increase the flow velocity of the free overfall jet and, in turn, to increase air entrainment. It was demonstrated that the air entrainment rate of the Venturi weir is significantly better than the rectangular notch weir, and this advantage becomes more pronounced as the throat width of the Venturi weir is decreased. These results demonstrated that Venturi weirs can be used as highly effective aerators in streams, rivers, constructed channels, fish hatcheries, water treatment plants, etc. Moreover, a regression equation was obtained for the Venturi weirs, relating air entrainment rate to unit discharge, weir crest width, drop height and throat width of Venturi weir. There was good agreement between the measured air entrainment rates and the values computed from the predictive equation.
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Lakusic, Stjepan. "The effect of crest shape on discharge coefficient at linear weirs." Journal of the Croatian Association of Civil Engineers 75, no. 07 (August 2023): 695–702. http://dx.doi.org/10.14256/jce.2027.2017.
Full textAbstract:
A detailed experimental laboratory analysis of the effect of crest shape on the discharge coefficient of sharp-crested weirs is presented in the paper. The experiments were conducted for four different crest shapes. The experiments and analyses show that discharge capacity, and discharge coefficient in particular, are significantly affected by weir crest height. It is stated in conclusion that rounded crest shape has the highest discharge capacity. In practice, sharp crested weirs are generally preferred to other crest shapes due to construction facility, although the discharge coefficient values of sharp crested weirs are lower compared to rounded crest shape.
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Uyumaz, A. "Flow Over Side Weirs in Rectangular and Circular Channels." Water Science and Technology 21, no. 8-9 (August 1, 1989): 739–46. http://dx.doi.org/10.2166/wst.1989.0277.
Full textAbstract:
Flow over side weirs in rectangular and circular channels is discussed. Numerical models are obtained from energy principles and are solved by a finite difference method. The results are presented in diagrammatic form for practical use. It is shown that rectangular channel side weir procedures cannot be used for obtaining approximate water surface profiles along the side weirs in circular channels.
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Mehri, Yaser, Jaber Soltani, Mojtaba Saneie, and Mohhamad Rostami. "Discharge Coefficient of a C-Type Piano Key Side Weir at 30° and 120° Sections of a Curved Channel." Civil Engineering Journal 4, no. 7 (August 2, 2018): 1702. http://dx.doi.org/10.28991/cej-03091106.
Full textAbstract:
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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El Hattab, Mohamad H., Ana Mijic, and Dejan Vernon. "Optimised Triangular Weir Design for Assessing the Full-Scale Performance of Green Infrastructure." Water 11, no. 4 (April 14, 2019): 773. http://dx.doi.org/10.3390/w11040773.
Full textAbstract:
Conventional triangular weirs have been originally developed to measure, divert, and control surface water. However, a special application of these weirs, such as for low flow measurements in full-scale monitoring of Green Infrastructure (GI), is not well investigated. Available head-discharge relationships for triangular sharp-crested weirs are only valid under a free-flow regime. Literature focusing on the V-notch weir usage for GI assessment suggests that it is necessary to calibrate the head-discharge relationship before its use. This study focuses on understanding the effects of site constraints on the measurement performance of a V-notch weir at low flow rates, and the validity of equations derived for similar applications that can be found in the literature. The variation of discharge coefficient in various flow regimes was investigated experimentally based on calibration runs covering flow rates between 0.054 l/s and 7 l/s. The results show that for 30° and 45° V-notch weirs, three flow regimes can be identified. It was observed that literature equations to calculate the discharge coefficient are valid for partially-contracted triangular weirs only at heads greater than vertex distance from the channel. However, for low flows that are expected to occur when estimating the full-scale performance of GI, the equations available from the literature for similar site conditions underestimated the flow rate between 85% and 17%. This emphasises the need for accurate calibration of a V-notch device under the site conditions to achieve the necessary level of accuracy in GI performance estimation. The procedure outlined in this work can be easily replicated to determine the optimal monitoring system configuration. Alternatively, if the site conditions would match those described in this study, the computed discharge using the proposed relations, in combination with the general V-notch weir equation, provides a significant improvement in the accuracy of measurements, expands the head applicability range of V-notch weirs, and enables better understanding of GI performance at the full scale.
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Vanishree, B. Rao, and R. Manjula. "Analysis of various parameters affecting weir design and fabrication of Weirs: An Overview." MATEC Web of Conferences 144 (2018): 01006. http://dx.doi.org/10.1051/matecconf/201814401006.
Full textAbstract:
Several geometric parameters influence weir discharge and it is explained in our present study. The PK weir is more efficient than rectangular labyrinth weir due to reduction in entrance losses of PK weir inlet key geometry. PK weir is a type of labyrinth weir with variation in angle. Therefore, in this paper we also discuss about labyrinth weir. PKW are compatible for constructing on existing or new spillway with lesser space requirement and structural stability. PKW are installed in order to increase the discharge capacity for a given footprint area. PKW is used to increase the overflow capacity of existing dams such as, Hazelmare dam (South Africa), Dartmouth dam (Australia). Trapezoidal piano key weirs have higher discharge efficiency than rectangular weirs and it is due to interference wedge. Cd of TPKW is influenced by L/W but Wi/Wo has least effect.
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Rood, Stewart B., and Amber Willcocks. "Duckling mortality at a river weir." Canadian Field-Naturalist 133, no. 2 (November 17, 2019): 167. http://dx.doi.org/10.22621/cfn.v133i2.2159.
Full textAbstract:
River weirs are low-head dams that dissipate energy by creating hydraulic recirculation zones at their base. These recirculation zones are a major cause of human drownings and have been referred to as “drowning machines”. We observed an event that allowed us to add ducklings to the list of weir victims. As a Mallard (Anas platyrhynchos) hen and her brood floated over the Calgary weir, the mother flew safely over the hydraulic recirculation. The ducklings drifted into the recirculation and three quickly passed through; four were stalled, repeatedly recirculated, and died. We observed other regional weirs where adult birds commonly flew over the hazard. We did not observe any other waterfowl drifting into recirculation zones, and we found no prior report of this lethal hazard. Although mortality might be rare at each weir, with hundreds of thousands of low-head dams worldwide, the collective hazard could be substantial. Weirs can be designed to eliminate the lethal recirculation zone, and the apparent hazard to ducklings could provide another motivation to redesign or modify these common structures.