Scour at a side-weir intersection located on an alluvial river

2007 ◽  
Vol 38 (2) ◽  
pp. 165-176 ◽  
Author(s):  
Fevzi Önen ◽  
Hayrullah Agaçcioglu
Keyword(s):  
Flow Velocity ◽  
Clear Water ◽  
Side Weir ◽  
Alluvial River ◽  
Sediment Size ◽  
Maximum Value ◽  
Water Head ◽  
Sand Bar ◽  
Side Weirs ◽  
Shear Stress Field

An experimental investigation of the equilibrium depth of local scour around side-weirs located on an alluvial river is presented in this paper. A sand bar in the middle of the channel and a scour hole close to the weir side is formed because of changes in shear stress field and velocity at the downstream end of the side weir. The depth of clear-water scour increases by time and approaches the equilibrium state asymptotically depending on approach flow velocity. The equilibrium depth of scour increases by the increase of the dimensionless parameters of approach flow velocity, water head ratio, side-weir length and sediment size. Although there is no scour for the dimensionless approach flow velocity less than 0.45, it increases almost linearly with the dimensionless approach flow velocity and the maximum value of scour depth occurs when it is equal to 1.0.

scholarly journals GEP PREDICTION OF SCOUR AROUND A SIDE WEIR IN CURVED CHANNEL

2014 ◽  
Vol 22 (3) ◽  
pp. 161-170 ◽  
Author(s):  
Fevzi Onen
Keyword(s):  
Gene Expression Programming ◽  
Distribution Channel ◽  
Regression Equation ◽  
Scour Depth ◽  
Curved Channel ◽  
Side Weir ◽  
Water Head ◽  
Dimensional Parameters ◽  
New Formulation ◽  
Side Weirs

Side-weirs have been widely used in hydraulic and environmental engineering applications. Side-weir is known as a lateral intake structure, which are significant parts of the distribution channel in irrigation, land drainage, and urban sewerage system, by flow diversion device. Local scour involves the removal of material around piers, abutments, side-weir, spurs, and embankments. Clearwater scour depth based on five dimensional parameters: approach flow velocity (V1/Vc), water head ratio (h1–p)/h1, side-weir length (L/r), side-weir crest height (b/p) and angle of bend θ. The aim of this study is to develop a new formulation for prediction of clear-water scour of side-weir intersection along curved channel using Gene Expression Programming (GEP) which is an algorithm based on genetic algorithms (GA) and genetic programming (GP). In addition, the explicit formulations of the developed GEP models are presented. Also equations are obtained using multiple linear regressions (MLR) and multiple nonlinear regressions (MNRL). The performance of GEP is found more influential than multiple linear regression equation for predicting the clearwater scour depth at side-weir intersection along curved channel. Multiple nonlinear regression equation was quite close to GEP, which serve much simpler model with explicit formulation.

Clear-water local scour at wide piers in shallow-water flow

2014 ◽  
Vol 9 (3) ◽  
pp. 331-343 ◽  
Author(s):  
N. Ahmad ◽  
T. Mohamed ◽  
F. H. Ali ◽  
B. Yusuf
Keyword(s):  
Laboratory Data ◽  
Local Scour ◽  
The Other ◽  
Scour Depth ◽  
Temporal Development ◽  
Clear Water ◽  
Shallow Water Flow ◽  
Equilibrium Time ◽  
Sediment Size ◽  
Flow Intensity

Laboratory data for local scour depth regarding the size of wide piers are presented. Clear water scour tests were performed for various pier widths (0.06, 0.076, 0.102, 0.14 and 0.165 m), two types of pier shapes (circular and rectangular) and two types of uniform cohesionless bed sediment (d50 = 0.23 and d50 = 0.80 mm). New data are presented and used to demonstrate the effects of pier width, pier shape and sediment size on scour depth. The influence of equilibrium time (te) on scouring processes is also discussed. Equilibrium scour depths were found to decrease with increasing values of b/d50. The temporal development of equilibrium local scour depth with new laboratory data is demonstrated for flow intensity V/Vc = 0.95. On the other hand, the results of scour mechanism have shown a significant relationship between normalized volume of scoured and deposited with pier width, b. The experimental data obtained in this study and data available from the literature for wide piers are used to evaluate predictions of existing methods.

Abutment scour in clear-water and live-bed conditions by GMDH network

2013 ◽  
Vol 67 (5) ◽  
pp. 1121-1128 ◽  
Author(s):  
Mohammad Najafzadeh ◽  
Gholam-Abbas Barani ◽  
Masoud Reza Hessami Kermani
Keyword(s):  
Back Propagation ◽  
Support Vector ◽  
Group Method ◽  
Scour Depth ◽  
Back Propagation Algorithm ◽  
Clear Water ◽  
Sediment Size ◽  
Svm Model ◽  
Vector Machines ◽  
Abutment Scour

In the present study, the Group Method of Data Handling (GMDH) network has been utilized to predict abutments scour depth for both clear-water and live-bed conditions. The GMDH network was developed using a Back Propagation algorithm (BP). Input parameters that were considered as effective variables on abutment scour depth included properties of sediment size, geometry of bridge abutments, and properties of approaching flow. Training and testing performances of the GMDH network were carried out using dimensionless parameters that were collected from the literature. The testing results were compared with those obtained using the Support Vector Machines (SVM) model and the traditional equations. The GMDH network predicted the abutment scour depth with lower error (RMSE (root mean square error) = 0.29 and MAPE (mean absolute percentage of error) = 0.99) and higher (R = 0.98) accuracy than those performed using the SVM model and the traditional equations.

Characteristics of the flow field in the combustion chamber of the internal combustion test engine

2011 ◽  
Vol 32 (3) ◽  
pp. 203-214 ◽  
Author(s):  
Wojciech Tutak ◽  
Arkadiusz Jamrozik
Keyword(s):  
Flow Field ◽  
Combustion Chamber ◽  
Flow Velocity ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Maximal Velocity ◽  
Maximum Value ◽  
Measurement Results ◽  
Test Engine ◽  
Fresh Charge

Characteristics of the flow field in the combustion chamber of the internal combustion test engine Results of a research study into the velocity field in combustion chamber of internal combustion engine are presented in the paper. Measurements of fresh charge flow velocity in the cylinder axis and near the cylinder squeezing surface were performed. The hot-wire anemometer was used. The measurement results were used for analysis of turbulence field in the examined combustion chamber. It turned out that in the axis of cylinder the maximum of velocity occurs 30 deg before TDC and achieves 6 m/s. In the studied combustion chamber, the maximum value of turbulence intensity was close to 0.2 and it was achieved 35 deg BTDC. Additionally, the maximal velocity dispersion in the following cycles of the researched engine was at the level of 2 m/s, which is 35% of the maximum value of flow velocity. At a point located near the squeezing surface of the piston, a similar level of turbulence, but a the smaller value of the average velocity was achieved. The turbulence field turned out to be inhomogeneous in the combustion chamber.

Clear-water scour at bridge piers in fine and medium gravel beds

2005 ◽  
Vol 32 (4) ◽  
pp. 775-781 ◽  
Author(s):  
Rajkumar V Raikar ◽  
Subhasish Dey
Keyword(s):  
Bridge Piers ◽  
Geometric Standard Deviation ◽  
Scour Depth ◽  
Size Factor ◽  
Clear Water ◽  
Envelope Curve ◽  
Gravel Beds ◽  
Sediment Size ◽  
Gravel Size ◽  
Equilibrium Scour Depth

An experimental investigation on scour at circular and square piers in uniform and non-uniform gravels (fine and medium sizes) under clear-water scour at limiting stability of gravels is presented. From the experimental results, it is observed that the equilibrium scour depth increases with decrease in gravel size. The variation of equilibrium scour depth with gravel sizes departures considerably from that with sand sizes. Consequently, the resulting sediment size factors for gravels, obtained from envelope curve fitting, are significantly different from the existing sediment size factor for sands. The influence of gravel gradation on scour depth is also prominent in non-uniform gravels. The time scales to represent the time variation of scour depth in uniform and non-uniform gravels are determined. For uniform gravels, the non-dimensional time scale increases with increase in pier Froude number and gravel size, whereas for non-uniform gravels, it decreases with increase in geometric standard deviation of particle size distribution of gravels.Key words: bridge pier, gravel beds, scour, erosion, sediment transport, open channel flow, hydraulic engineering.

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.

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.

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.

Pressure flow and weir scour beneath a bridge deck

2019 ◽  
Vol 46 (6) ◽  
pp. 534-543
Author(s):  
Musteyde Baduna Kocyigit ◽  
Onur Karakurt
Keyword(s):  
Bridge Deck ◽  
Flow Depth ◽  
Clear Water ◽  
Hole Depth ◽  
Sediment Size ◽  
Bridge Model ◽  
Weir Flow ◽  
Water Conditions ◽  
Scour Hole ◽  
Series Of Experiments

In this study, a series of experiments in a flume was conducted to investigate the maximum scour hole depth that occurred due to the vertical contraction of the flow underneath a bridge deck model without a pier. The bridge model was tested under pressurized and weir type of flows governed by clear water conditions. Various parameters of flow, sediment, and geometric features of the bridge, such as approach flow depth, discharge, sediment size, girder depth and degree of submergence were varied to investigate their effects on the maximum depth of scour hole. A total of 102 experiments were conducted and two empirical equations were developed separately for pressure and weir flow types with the use of experimental data. Effects of the aforementioned parameters on the scour hole were also analyzed and discussed.

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