scholarly journals Estimation of hydraulic jump characteristics of channels with sudden diverging side walls via SVM

2017 ◽  
Vol 76 (7) ◽  
pp. 1614-1628 ◽  
Author(s):  
Kiyoumars Roushangar ◽  
Reyhaneh Valizadeh ◽  
Roghayeh Ghasempour
Keyword(s):  
Froude Number ◽  
Hydraulic Jump ◽  
Relative Energy ◽  
Expansion Ratio ◽  
Superior Performance ◽  
Support Vector ◽  
Great Performance ◽  
Stilling Basins ◽  
Side Walls ◽  
Sequent Depth

Sudden diverging channels are one of the energy dissipaters which can dissipate most of the kinetic energy of the flow through a hydraulic jump. An accurate prediction of hydraulic jump characteristics is an important step in designing hydraulic structures. This paper focuses on the capability of the support vector machine (SVM) as a meta-model approach for predicting hydraulic jump characteristics in different sudden diverging stilling basins (i.e. basins with and without appurtenances). In this regard, different models were developed and tested using 1,018 experimental data. The obtained results proved the capability of the SVM technique in predicting hydraulic jump characteristics and it was found that the developed models for a channel with a central block performed more successfully than models for channels without appurtenances or with a negative step. The superior performance for the length of hydraulic jump was obtained for the model with parameters F1 (Froude number) and (h2—h1)/h1 (h1 and h2 are sequent depth of upstream and downstream respectively). Concerning the relative energy dissipation and sequent depth ratio, the model with parameters F1 and h1/B (B is expansion ratio) led to the best results. According to the outcome of sensitivity analysis, Froude number had the most significant effect on the modeling. Also comparison between SVM and empirical equations indicated the great performance of the SVM.

scholarly journals Evaluation of the impact of channel geometry and rough elements arrangement in hydraulic jump energy dissipation via SVM

2018 ◽  
Vol 21 (1) ◽  
pp. 92-103 ◽  
Author(s):  
Kiyoumars Roushangar ◽  
Roghayeh Ghasempour
Keyword(s):  
Energy Dissipation ◽  
Dimensional Analysis ◽  
Hydraulic Jump ◽  
Relative Energy ◽  
Superior Performance ◽  
Support Vector ◽  
Data Series ◽  
Rough Boundary ◽  
Channel Geometry ◽  
The Impact

Abstract Rough bed channels are one of the appurtenances used to dissipate the extra energy of the flow through hydraulic jump. The aim of this paper is to assess the effects of channel geometry and rough boundary conditions (i.e., rectangular, trapezoidal, and expanding channels with different rough elements) in predicting the hydraulic jump energy dissipation using support vector machine (SVM) as a meta-model approach. Using different experimental data series, different models were developed with and without considering dimensional analysis. The results approved capability of the SVM model in predicting the relative energy dissipation. It was found that the developed models for expanding channel with central sill performed more successfully and, for this case, superior performance was obtained for the model with parameters Fr1 and h1/B. Considering the rectangular and trapezoidal channels, the model with parameters Fr1, (h2−h1)/h1, W/Z led to better predictions. It was observed that between two types of strip and staggered rough elements, strip type led to more accurate results. The obtained results showed that the developed models for the case of simulation based on dimensional analysis yielded better predictions. The sensitivity analysis results showed that Froude number had the most significant impact on the modeling.

scholarly journals Explicit prediction of expanding channels hydraulic jump characteristics using gene expression programming approach

2017 ◽  
Vol 49 (3) ◽  
pp. 815-830 ◽  
Author(s):  
Kiyoumars Roushangar ◽  
Roghayeh Ghasempour
Keyword(s):  
Gene Expression ◽  
Hydraulic Jump ◽  
Gene Expression Programming ◽  
Relative Energy ◽  
Expansion Ratio ◽  
Programming Approach ◽  
Jump Length ◽  
Input Parameters ◽  
Sequent Depth ◽  
Better Than

Abstract Hydraulic jump is a useful means of dissipating excess energy of a supercritical flow so that objectionable scour downstream is minimized. The present study applies gene expression programming (GEP) to estimate hydraulic jump characteristics in sudden expanding channels. Three types of expanding channels were considered: channels without appurtenances, with a central sill, and with a negative step. 1,000 experimental data were considered as input data to develop models. The results proved the capability of GEP in predicting hydraulic jump characteristics in expanding channels. It was found that the developed models for channel with a central sill performed better than other channels. In the jump length prediction, the model with input parameters Fr1 and (y2—y1)/y1, and in the sequent depth ratio and relative energy dissipation prediction the model with input parameters Fr1 and y1/B led to more accurate outcomes (Fr1, y1, y2, and B are Froude number, sequent depth of upstream and downstream, and expansion ratio, respectively). Sensitivity analysis showed that Fr1 had the key role in modeling. The GEP models were compared with existing empirical equations and it was found that the GEP models yielded better results. It was also observed that channel and appurtenances geometry affected the modeling.

scholarly journals Pressure Fluctuations in the Spatial Hydraulic Jump in Stilling Basins with Different Expansion Ratio

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 60
Author(s):  
Nasrin Hassanpour ◽  
Ali Hosseinzadeh Dalir ◽  
Arnau Bayon ◽  
Milad Abdollahpour
Keyword(s):  
Hydraulic Jump ◽  
Laboratory Tests ◽  
Pressure Fluctuations ◽  
Expansion Ratio ◽  
Hydraulic Jumps ◽  
Extreme Pressure ◽  
Flow Conditions ◽  
Stilling Basins ◽  
Channel Expansion ◽  
Shed Light

Pressure fluctuations are a key issue in hydraulic engineering. However, despite the large number of studies on the topic, their role in spatial hydraulic jumps is not yet fully understood. The results herein shed light on the formation of eddies and the derived pressure fluctuations in stilling basins with different expansion ratios. Laboratory tests are conducted in a horizontal rectangular flume with 0.5 m width and 10 m length. The range of approaching Froude numbers spans from 6.4 to 12.5 and the channel expansion ratios are 0.4, 0.6, 0.8, and 1. The effects of approaching flow conditions and expansion ratios are thoroughly analyzed, focusing on the dimensionless standard deviation of pressure fluctuations and extreme pressure fluctuations. The results reveal that these variables show a clear dependence on the Froude number and the distance to the hydraulic jump toe. The maximum values of extreme pressure fluctuations occur in the range 0.609<X<3.385, where X is dimensionless distance from the toe of the hydraulic jump, which makes it highly advisable to reinforce the bed of stilling basins within this range.

scholarly journals Experimental study and modeling of hydraulic jump for a suddenly expanding stilling basin using different hybrid algorithms

2021 ◽  
Author(s):  
Enes Gul ◽  
O. Faruk Dursun ◽  
Abdolmajid Mohammadian
Keyword(s):  
Experimental Study ◽  
Hydraulic Jump ◽  
Imperialist Competitive Algorithm ◽  
Expansion Ratio ◽  
Stilling Basin ◽  
Jump Length ◽  
Depth Ratio ◽  
Input Variables ◽  
Sequent Depth ◽  
Learning Machine

Abstract Hydraulic jump is a highly important phenomenon for dissipation of energy. This event, which involves flow regime change, can occur in many different types of stilling basins. In this study, hydraulic jump characteristics such as relative jump length and sequent depth ratio occurring in a suddenly expanding stilling basin were estimated using hybrid Extreme Learning Machine (ELM). To hybridize ELM, Imperialist Competitive Algorithm (ICA), Firefly Algorithm (FA) and Particle Swarm Optimization (PSO) metaheuristic algorithms were implemented. In addition, six different models were established to determine effective dimensionless (relative) input variables. A new dataset was constructed by adding the data obtained from the experimental study in the present research to the data obtained from the literature. The performance of each model was evaluated using k-fold cross validation. Results showed that ICA hybridization slightly outperformed FA and PSO methods. Considering relative input parameters, Froude number (Fr), expansion ratio (B) and relative sill height (S), and effective input combinations were Fr – B– S and Fr – B for the prediction of the sequent depth ratio (Y) and relative hydraulic jump length (Lj/h1), respectively.

scholarly journals Uncertainty analyses regarding evaluating effective parameters on the hydraulic jump characteristics of different shape channels

2021 ◽  
Author(s):  
Kiyoumars Roushangar ◽  
Farzin Homayounfar ◽  
Roghayeh Ghasempour
Keyword(s):  
Hydraulic Jump ◽  
Gaussian Process Regression ◽  
Support Vector ◽  
Hydraulic Jumps ◽  
Empirical Equations ◽  
Effective Parameters ◽  
Jump Length ◽  
Depth Ratio ◽  
Sequent Depth ◽  
Semi Empirical

Abstract The hydraulic jump phenomenon is a beneficial tool in open channels for dissipating the extra energy of the flow. The sequent depth ratio and hydraulic jump length critically contribute to designing hydraulic structures. In this research, the capability of Support Vector Machine (SVM) and Gaussian Process Regression (GPR) as kernel-based approaches was evaluated to estimate the features of submerged and free hydraulic jumps in channels with rough elements and various shapes, followed by comparing the findings of GPR and SVM models and the semi-empirical equations. The results represented the effect of the geometry (i.e., steps and roughness elements) of the applied appurtenances on hydraulic jump features in channels with appurtenances. Moreover, the findings confirmed the significance of the upstream Froude number in the sequent depth ratio estimating in submerged and free hydraulic jumps. In addition, the immersion was the highest contributing variable regarding the submerged jump length on sloped smooth bed and horizontal channels. Based on the comparisons among kernel-based approaches and the semi-empirical equations, kernel-based models showed better performance than these equations. Finally, an uncertainty analysis was conducted to assess the dependability of the best applied model. The results revealed that the GRP model possesses an acceptable level of uncertainty in the modeling process.

scholarly journals Predicting the relative energy dissipation of hydraulic jump in rough and smooth bed compound channels using SVM

2018 ◽  
Vol 19 (4) ◽  
pp. 1110-1119
Author(s):  
Seyed Mahdi Saghebian
Keyword(s):  
Energy Dissipation ◽  
Hydraulic Jump ◽  
Dominant Role ◽  
Rectangular Channel ◽  
Relative Energy ◽  
Support Vector ◽  
Channel Models ◽  
Rough Bed ◽  
Different Shapes ◽  
Rough Beds

Abstract Channels with different shapes and bed conditions are used as useful appurtenances to dissipate the extra energy of a hydraulic jump. Accurate prediction of hydraulic jump energy dissipation is important in design of hydraulic structures. In the current study, hydraulic jump energy dissipation was assessed in channels with different shapes and bed conditions (i.e. smooth and rough beds) using the support vector machine (SVM) as an intelligence approach. Five series of experimental datasets were applied to develop the models. The results showed that the SVM model is successful in estimating the relative energy dissipation. For the smooth bed, it was observed that the sloping channel models with steps performed more successfully than rectangular and trapezoidal channels and the step height is an effective variable in the estimation process. For the rough bed, the trapezoidal channel models were more accurate than the rectangular channel. It was found that rough element geometry is effective in estimation of the energy dissipation. The result showed that the models of rough channels led to better predictions. The sensitivity analysis results revealed that Froude number had the more dominant role in the modeling. Comparison among SVM and two other intelligence approaches showed that SVM is more successful in the prediction process.

Hydraulic jump in a sloped triangular channel

2009 ◽  
Vol 36 (4) ◽  
pp. 655-658 ◽  
Author(s):  
Mahmoud Debabeche ◽  
Sonia Cherhabil ◽  
Amin Hafnaoui ◽  
Bachir Achour
Keyword(s):  
Froude Number ◽  
Experimental Analysis ◽  
Hydraulic Jump ◽  
Central Angle ◽  
Theoretical Relation ◽  
Triangular Channel ◽  
Depth Ratio ◽  
Channel Slope ◽  
Sequent Depth

The hydraulic jump in a sloped triangular channel of 90° central angle is theoretically and experimentally examined. The study aims to determine the effect of the channel's slope on the sequent depth ratio of the jump. A theoretical relation is proposed for the inflow Froude number as function of the sequent depth ratio and the channel slope. An experimental analysis is also proposed to find a better formulation of the obtained relation. For this motive, six positive slopes are tested. The relations obtained are recommended for designing irrigation ditches.

scholarly journals The performance of hydraulic jump over rough bed stilling basin consisting of cubic-shape elements

2018 ◽  
Vol 162 ◽  
pp. 03001
Author(s):  
Jaafar Maatooq ◽  
Enass Taleb
Keyword(s):  
Hydraulic Jump ◽  
Relative Energy ◽  
Stilling Basin ◽  
Depth Ratio ◽  
Roughness Elements ◽  
Rough Bed ◽  
Specific Configuration ◽  
Experimental Works ◽  
Sequent Depth ◽  
Group Configuration

Three groups of cubic roughness elements non-protruding to the flow were fixed with a specific configuration at the downstream of a stream lined lib sluice gate. The aim was to test the performance of the hydraulic jump under using such elements as appurtenances of stilling basin. The experimental works has been conducting to test; four different intensities, I=8%, 10%, 12% and 16%; three width to height ratios, We/he=0.75, 1.5 and 2; and three length to height ratios, Le/he=0.75, 2 and 4, of cubic elements made from waterproof stiff rubber. The test was performed under the incoming Froude number; F1 ranged between 2.7 to 9. After analysing the experimental data one from the second group configuration gives a higher reduction of sequent depth ratio, y2/y1 as compared with the depth ratio of the un-forced hydraulic jump which calculated by Belanger equation, this decreases arrived 20%. Also greater relative energy has been dissipated, and the gain in dissipation (%GED) ranged between 10.8-22.3%.

scholarly journals Effect of baffle block configurations on characteristics of hydraulic jump in adverse stilling basins

2018 ◽  
Vol 162 ◽  
pp. 03005
Author(s):  
Ali Abbas ◽  
Haider Alwash ◽  
Ali Mahmood
Keyword(s):  
Energy Dissipation ◽  
Hydraulic Jump ◽  
Block Model ◽  
Double Row ◽  
Stilling Basin ◽  
Depth Ratio ◽  
Stilling Basins ◽  
Sequent Depth ◽  
Baffle Block ◽  
Energy Dissipation Ratio

The construction of stilling basin with adverse slope change the characteristics of hydraulic jump such as sequent depth ratio, length of jump ratio, length of roller and energy dissipation ratio, consequently the dimensions of stilling basin are changed, also using baffle blocks with different configurations develop these characteristics. In this study different shapes of baffle block (models (A), (B), (C) and (D)) installed in the stilling basins at adverse slopes (- 0.03, - 0.045, - 0.06) in addition to horizontal bed, all these models are tested in the stilling basin to show their effects on the characteristics of hydraulic jump, the experiments applied for the range of Froude number (Fr1) between 3.99 and 7.48. The baffle block model (D) showed good results when compared with models (B) and (C), therefore it used with arrangement of (single and double row) and compared with baffle block model (A) at slopes (0, - 0.03, - 0.045, - 0.06) to study the effects of baffle blocks on hydraulic jump when bed slopes are changed. In general using baffle block caused a reduction in sequent depth ratio, length of jump ratio and the length of the roller, but the energy dissipation ratio increased.

scholarly journals Hydraulic Jump below Abrupt Asymmetric Expanding Stilling Basin on Rough Bed

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1756 ◽  
Author(s):  
Nafiseh Torkamanzad ◽  
Ali Hosseinzadeh Dalir ◽  
Farzin Salmasi ◽  
Akram Abbaspour
Keyword(s):  
Hydraulic Jump ◽  
Expansion Ratio ◽  
Physical Models ◽  
Empirical Relationships ◽  
Stilling Basin ◽  
Roughness Elements ◽  
Rough Bed ◽  
Effective Role ◽  
Bed Roughness ◽  
Sequent Depth

The present research describes a laboratory study of hydraulic jump in the abrupt asymmetric expansion stilling basin as an energy dissipator by changing the geometry of walls and bed roughness elements. The experiments were carried out in a horizontal flume with 10 m length, 0.5 m width, and 0.5 m depth for a range of the upstream Froude numbers ( F r 1 ) from 5 to 11. Four physical models with expansion ratio of α   = 0.33, 0.5, 0.67, and 1 and asymmetry ratio of Δ = 0.16 were installed in the flume and two different heights of roughness elements ( h   = 1.4 and 2.8 cm) were also considered. The results indicated that the sequent depth and the jump length as well as the roller length below abrupt asymmetric expansion on the rough bed were decreased in comparison to the same parameters of the jump in a prismatic channel with smooth bed. It was revealed that the roughness elements have the effective role on stabilization of the hydraulic jump location. The analysis of energy dissipation efficiency confirmed that the spatial jump in the abruptly expanded basin with roughened bed was more efficient than classical jump. In order to estimate the hydraulic jump characteristics, empirical relationships associated with expansion ratio of basin walls, relative height of roughness elements and upstream Froude number were proposed based on the experimental data that resulted in preliminary design of an abrupt asymmetric enlarged basin.

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