Velocity Distribution and Attenuation Characteristic in Hydraulic Jumps on Rough Beds

2021 ◽  
Author(s):  
Lei Wang ◽  
Ming-jun Diao
Keyword(s):  
Velocity Distribution ◽  
Hydraulic Jump ◽  
Maximum Velocity ◽  
Hydraulic Jumps ◽  
Attenuation Characteristic ◽  
Jump Length ◽  
Attenuation Rate ◽  
Rough Bed ◽  
Velocity Attenuation ◽  
Rough Beds

This study was conducted to investigate the velocity distribution and attenuation in free jumps on rough beds. Based on the length scale of jump length Lj, the velocity distribution of the free jump on a rough bed can be divided into four parts by three typical sections where are in the position of x=0.4Lj, x=0.8Lj, and x=1.2Lj. It seems that the velocity distribution near section x=0.4Lj is the most uneven. The velocity attenuation rate in the bottom half of the water is larger than that in the top half of the water. The attenuation of the maximum velocity um is mainly done from x=0 to x=0.8Lj. The results show the mixed triangular corrugated floor increases the resistance of hydraulic jump development and is very efficient in energy dissipation.

scholarly journals Numerical Simulation of Hydraulic Jump over Rough Beds

2020 ◽  
Author(s):  
Saman Nikmehr ◽  
Younes Aminpour
Keyword(s):  
Numerical Model ◽  
Velocity Distribution ◽  
Hydraulic Jump ◽  
Surface Profile ◽  
Jump Length ◽  
Rough Bed ◽  
Sequent Depth ◽  
Rough Beds ◽  
Different Characteristics ◽  
Good Agreement

In this study, the hydraulic jumps over rough beds are numerically simulated. In order to calibrate the numerical model, the experimental data were used, which performed in a rectangular flume in various roughness arrangements and different Froude numbers. The effect of the distance (s) and the height (t) of the roughness on different characteristics of the hydraulic jump, including the sequent depth ratio, water surface profile, jump’s length, roller’s length, and velocity distribution were evaluated and compared. The results showed that the numerical model is fairly well able to simulate the hydraulic jump characteristics. The results also showed that the height and distance of roughness slightly reduced the sequent depth ratios for all Froude numbers. Also, the hydraulic jump length is reduced at the presence of the rough bed. Velocity profiles in different experiments were similar and there was a good agreement between simulated and measured results. Also, increasing the distance and the height of the roughness will slow down the velocity near the bed, increase the shear stress, and increase the gradient of the velocity distribution near the bed.

scholarly journals Effect of roughness on sequent depth in hydraulic jumps over rough bed

2019 ◽  
Vol 71 (2) ◽  
pp. 105-111
Author(s):  
Arpan Arunrao Deshmukh ◽  
Naveen Sudharsan ◽  
Avinash D Vasudeo ◽  
Aniruddha Dattatraya Ghare
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Hydraulic Jump ◽  
Open Channel ◽  
Hydraulic Jumps ◽  
Open Channel Flows ◽  
Downstream Side ◽  
Rough Bed ◽  
Sequent Depth ◽  
Rough Beds

Hydraulic jump is an important phenomenon in open channel flows such as rivers and spillways. Hydraulic jump is mainly used for kinetic energy dissipation at the downstream side of a spillway with the assist of baffle blocks. It has been demonstrated that corrugated or rough beds show considerably more energy dissipation than smooth beds. The experimental research evaluating the effect of crushed stones on the hydraulic jump is presented in this paper. Five different-size sets of crushed stones were used. Results show that the effect of rough bed does not increase after a certain height of crushed stone is reached.

scholarly journals Measurement of turbulent flow in a narrow open channel

2016 ◽  
Vol 64 (3) ◽  
pp. 273-280 ◽  
Author(s):  
Sankar Sarkar
Keyword(s):  
Turbulent Flow ◽  
Reynolds Shear Stress ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Turbulent Characteristics ◽  
Stress Changes ◽  
Rough Bed ◽  
Median Diameter ◽  
Rough Beds ◽  
Bed Material

Abstract The paper presents the experimental results of turbulent flow over hydraulically smooth and rough beds. Experiments were conducted in a rectangular flume under the aspect ratio b/h = 2 (b = width of the channel 0.5 m, and h = flow depth 0.25 m) for both the bed conditions. For the hydraulically rough bed, the roughness was created by using 3/8″ commercially available angular crushed stone chips; whereas sand of a median diameter d50 = 1.9 mm was used as the bed material for hydraulically smooth bed. The three-dimensional velocity components were captured by using a Vectrino (an acoustic Doppler velocimeter). The study focuses mainly on the turbulent characteristics within the dip that were observed towards the sidewall (corner) of the channel where the maximum velocity occurs below the free-surface. It was also observed that the nondimensional Reynolds shear stress changes its sign from positive to negative within the dip. The quadrant plots for the turbulent bursting shows that the signs of all the bursting events change within the dip. Below the dip, the probability of the occurrence of sweeps and ejections are more than that of inward and outward interactions. On the other hand, within the dip, the probability of the occurrence of the outward and inward interactions is more than that of sweeps and ejections.

Radial flow stilling basins with baffle blocks

1989 ◽  
Vol 16 (4) ◽  
pp. 489-497 ◽  
Author(s):  
Peter C. Nettleton ◽  
John A. McCorquodale
Keyword(s):  
Key Words ◽  
Hydraulic Jump ◽  
Water Surface ◽  
Radial Flow ◽  
Surface Profile ◽  
Hydraulic Jumps ◽  
Bureau Of Reclamation ◽  
Stilling Basin ◽  
Jump Length ◽  
Stilling Basins

A total of 120 tests of forced radial flow hydraulic jumps have been analyzed in order to develop curves and equations for the design of radial stilling basins. The jump depth, the water surface profile, wave amplitudes, the allowable flare angle, and the jump length are defined in terms of entrance conditions, the baffle position, and the baffle height. An example design is given and compared with a USBR (U.S. Bureau of Reclamation) Type III stilling basin. Key words: forced hydraulic jump, radial flow, design, stilling basins, baffles, radial hydraulic jump, circular hydraulic jump.

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.

Analysis of the submerged radial hydraulic jump

1985 ◽  
Vol 12 (3) ◽  
pp. 593-602 ◽  
Author(s):  
Sameh M. Abdel-Gawad ◽  
John A. McCorquodale
Keyword(s):  
Velocity Distribution ◽  
Internal Flow ◽  
Operating Conditions ◽  
Surface Velocity ◽  
Velocity Variation ◽  
Experimental Program ◽  
Hydraulic Jumps ◽  
Jump Length ◽  
Depth Ratio ◽  
Sequent Depth

Most of the research work on hydraulic jumps has dealt with their macroscopic behaviour. The important parameters in these studies were the sequent depth ratio and the jump length required for stilling basin design. Unfortunately, the internal flow in submerged radial hydraulic jumps has received very little attention. A complete mathematical model of the internal flow would permit the modeller to assess the possible scale effects in a physical model and to better estimate the cavitation potential.This study treats the internal flow characteristics of the submerged radial hydraulic jumps under different submergence and operating conditions. A numerical model based on the strip integral method is used to solve the governing momentum and continuity equations. The numerical technique uses velocity shape functions to permit the partial integration of the equations of motion. A Gaussian velocity distribution is used in the mixing zone and the power law is used in the inner layer. The model predicts the velocity distribution, water surface profile, decay of the maximum velocity, variation of the surface velocity, sequent depth ratio, jump length, and energy loss.A comprehensive experimental program was conducted in an expanding Plexiglas flume with a total angle of divergence of 13.5°. The results were used to calibrate and validate the model. The model predictions also compared well with the results of other studies.

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