Effect of grain size on local channel scour below a sluice gate

2001 ◽  
Vol 28 (3) ◽  
pp. 440-451 ◽  
Author(s):  
J A Kells ◽  
R Balachandar ◽  
K P Hagel
Keyword(s):  
Grain Size ◽  
Flow Rate ◽  
Image Data ◽  
Local Scour ◽  
Scour Depth ◽  
Sluice Gate ◽  
Time Period ◽  
Depth Video ◽  
Bed Material ◽  
Cohesive Bed

In this study, the effect of grain size on the dynamics of local scour processes is discussed in the context of the erosion that takes place downstream from a submerged sluice gate. Four gradations of non-cohesive bed material were used to study the scour process for various tailwater depth and flow rate conditions. The sand gradations included three sizes of uniformly graded sand and a fourth size, which was obtained by mixing the three uniform sands in equal proportions by weight. A total of 36 tests was carried out, each for a period of 24 h. An equilibrium scour condition was not attained over this time period for any of the tests, although a sense of similarity in the bed profiles is observed in the region close to the sluice gate. The present results indicate that the depth and the area of scour are highly dependent on the bed grain size, both increasing as the grain size is reduced. As well, it was found that the tests with a mixed (i.e., graded) sand bed resulted in less scour relative to those in which a uniformly graded sand of similar grain size was used. Moreover, the maximum scour depth increases with increases in the discharge and the tailwater depth. Finally, it was found that the location of the point of maximum scour depth, as measured from the upstream end of the erodible sand bed, moved downstream with an increase in either the discharge or tailwater depth and upstream with an increase in the grain size.Key words: grain size, grain size distribution, local scour, scour dynamics, sluice gate, tailwater depth, video image data acquisition.

scholarly journals Open Channel Sluice Gate Scouring Parameters Prediction: Different Scenarios of Dimensional and Non-Dimensional Input Parameters

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 353 ◽  
Author(s):  
Ali Yousif ◽  
Sadeq Sulaiman ◽  
Lamine Diop ◽  
Mohammad Ehteram ◽  
Shamsuddin Shahid ◽  
...  
Keyword(s):  
Scour Depth ◽  
Sluice Gate ◽  
Analysis Technique ◽  
Dimensionless Groups ◽  
Scour Hole ◽  
Adaptive Regression ◽  
Learning Machine ◽  
Bed Material ◽  
Statistical Metrics

The determination of scour characteristics in the downstream of sluice gate is highly important for designing and protection of hydraulic structure. The applicability of modern data-intelligence technique known as extreme learning machine (ELM) to simulate scour characteristics has been examined in this study. Three major characteristics of scour hole in the downstream of a sluice gate, namely the length of scour hole (Ls), the maximum scour depth (Ds), and the position of maximum scour depth (Lsm), are modeled using different properties of the flow and bed material. The obtained results using ELM were compared with multivariate adaptive regression spline (MARS). The dimensional analysis technique was used to reduce the number of input variable to a smaller number of dimensionless groups and both the dimensional and non-dimensional variables were used to model the scour characteristics. The prediction performances of the developed models were examined using several statistical metrics. The results revealed that ELM can predict scour properties with much higher accuracy compared to MARS. The errors in prediction can be reduced in the range of 79%–81% using ELM models compared to MARS models. Better performance of the models was observed when dimensional variables were used as input. The result indicates that the use of ELM with non-dimensional data can provide high accuracy in modeling complex hydrological problems.

scholarly journals An Examination of the Dependency between Maximum Equilibrium Local Scour Depth and the Grain Size/Structure Size Ratio

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3117
Author(s):  
Raphael Crowley ◽  
William Cottrell ◽  
Alexander Singleton
Keyword(s):  
Grain Size ◽  
Pressure Gradient ◽  
Size Structure ◽  
Local Equilibrium ◽  
Local Scour ◽  
Size Ratio ◽  
Grain Structure ◽  
Scour Depth ◽  
Equilibrium Scour Depth ◽  
New Formulation

This paper begins by demonstrating how the Florida Department of Transportation (FDOT) local scour equations take the ratio between grain size and structure size into account when computing equilibrium local scour depth and contrasts this with the well-known Colorado State University (CSU) equation that does not take sediment information into account. Then, a relatively recent empirical formulation from the J-L. Briaud research group for computing local equilibrium scour depth is presented that appears to take the structure size/grain size ratio into account indirectly. Next, a possible explanation for the dependency between local equilibrium scour depth and the structure/grain size ratio is presented that was originally developed by D. Max Sheppard in 2004. This explanation shows that superimposing the pressure gradient around a particle with the pressure gradient around a pile leads to the dependency between equilibrium scour depth and the grain size/structure size ratio. Finally, a new formulation for local equilibrium scour depth based upon turbulent energy spectrum decay is presented. This new formulation reduces the local scour problem to a problem whereby turbulent diffusivity must be better understood. However, this new formulation also appears to show a dependency between equilibrium scour depth and the grain size/structure size ratio. Overall, the analysis presented herein provides several reasons, explanations, and pieces of evidence to suggest that the grain/structure size ratio is an important parameter to consider when computing local equilibrium scour depth.

An experimental study into local scour in a channel caused by a 90° bend

2006 ◽  
Vol 33 (7) ◽  
pp. 902-911 ◽  
Author(s):  
Jueyi Sui ◽  
Daxian Fang ◽  
Bryan W Karney
Keyword(s):  
Froude Number ◽  
Flow Direction ◽  
Local Scour ◽  
Scour Depth ◽  
Factors Affecting ◽  
Downstream Section ◽  
Series Of Experiments ◽  
Bed Material ◽  
Hydraulic Variables

Based on a series of experiments, this paper explores the influence of a 90° change in flow direction on local scouring. The influence on local scour patterns due to hydraulic parameters such as the Froude number, the slope of the protection wall, the width of the protection apron along the outside wall of the downstream section, and the grain size of the channel bed material is examined. Protection-wall slopes ranging from 1:0.5 to 1:4 (vertical to horizontal) were investigated, as were different widths of the protection apron; the goal was to ascertain the role of these variables in local scour patterns in the vicinity of the bend. The factors affecting local scour depth are related through empirical equations to key hydraulic variables, the slope of the protection wall, and the width of the protection apron.Key words: bent flume, channel erosion, Froude number, scour depth, slope of protection wall (SPW), width of protection apron (WPA).

scholarly journals The influence of sandy clay bed material to local scour behaviour

2017 ◽  
Vol 35 (1) ◽  
pp. 193-202
Author(s):  
Nina B. Rustiati ◽  
Very Dermawan ◽  
R. Rispiningtati ◽  
Lily M. Limantara
Keyword(s):  
Water Level ◽  
Open Channel ◽  
Flow Model ◽  
Local Scour ◽  
Coefficient Of Determination ◽  
Sluice Gate ◽  
Gate Opening ◽  
Bed Material ◽  
The Relationship

Abstract As a type of gate that is used to control the water level upstream, sluice gate is the gate with simple shape and outstanding ability to flush the sediment. The operation of the gate is considered an important process. The up and down movement of the gate would affect the velocity and cause local scour as the result of fluctuating rate. This research aims to assess the effects of discharge and gate-opening height variations, as well as the type of bedchannel material, on the change of depth of scour (ds). The research was conducted of open channel flow model with a sluice gate able to up and down movement. The discharges used in the research were 9 types ranging from 1.0 to 5.0 dm3·s−1. There were 5 variations in the height of gate-opening ranging from 0.5 to 2.5 cm at intervals of 0.5 and types of channel-bed material. The results of the research showed that the depth of scour can be analysed as a function of discharge, height of gate-opening, height of water level upstream and downstream, and the type of bed material used. The scour depth equation on is $d_s = 1.7822\left( {{Q \over a}} \right)^{1.1347} a$ . Calculated coefficient of determination of the relationship between two types of channel-bed material and the depth of scour was R2 = 0.946. Consequently, it can be concluded that the equation can be applied on both types of bed-channel material.

scholarly journals Time Dependent Live-bed Scour Around Circular Piers under Flood Waves

2019 ◽  
Author(s):  
Firat Gumgum ◽  
Mehmet Sukru Guney
Keyword(s):  
Flow Rate ◽  
Peak Flow ◽  
Time Dependent ◽  
Scour Depth ◽  
Empirical Equations ◽  
Peak Flow Rate ◽  
Bed Scour ◽  
Different Diameters ◽  
Bed Material ◽  
Flood Waves

The aim of this study is to investigate live-bed scour under unsteady flow. During the experiments, 16 different triangular hydrographs were generated. Circular piers with three different diameters were tested under these hydrographs. Uniform bed material of 1.63 mm diameter was used during the experiments. The effects of the peak flow rate, the duration of hydrographs and the pier diameter on scour were interpreted. It was observed that the dominant element of the scour was the flow rate during the rising limb and the sediment transport rate during the falling limb. Maximum scour depths took place near the peak flow and lower final scour depths occurred at the end of the hydrograph. Two empirical equations were derived to predict time dependent scour depth and maximum scour depth. Statistically significant determination coefficient values and scatter indices were obtained.

Effect of Gradation of Bed Material on Local Scour Depth

2018 ◽  
Vol 36 (4) ◽  
pp. 2505-2516 ◽  
Author(s):  
Bintul Huda Mir ◽  
Mohd Akbar Lone ◽  
Javeed Ahmad Bhat ◽  
Nasir Ahmad Rather
Keyword(s):  
Local Scour ◽  
Scour Depth ◽  
Bed Material
Sign in / Sign up

Export Citation Format

Share Document