Hydraulic jumps on rough and smooth beds: aggregate approach for horizontal and adverse-sloped beds

Pagliara, Stefano; Palermo, Michele

doi:10.1080/00221686.2015.1017778

Cited by 48 publications

(50 citation statements)

References 23 publications

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“…The data were overall in agreement with previous studies of roughness effects (e.g. Hughes and Flack 1984;Carollo et al 2007;Afzal et al 2011;Pagliara and Palermo 2015). The present data for the two rough bed configurations were in good agreement and no downwards shift of the conjugate depth relationship was observed for rough bed 2.…”

Section: Free-surface Characteristicssupporting

confidence: 83%

“…This finding differed from previous studies, showing a downward shift of conjugate depth ratio with increasing equivalent sand roughness height (e.g. Carollo et al 2007;Afzal et al 2011;Pagliara and Palermo 2015). It is believed that the exact definition of d1 may have had an impact upon the conjugate depth relationship: i.e., specifically the measurement of the free-surface with a pointer gauge in previous studies and possibly the definition of the zero position in rough bed 2 in the present study.…”

Section: Free-surface Characteristicscontrasting

confidence: 56%

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Air–Water Flow Patterns of Hydraulic Jumps on Uniform Beds Macroroughness

Felder

Chanson

2018

J. Hydraul. Eng.

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Hydraulic jumps are characterised by strong flow turbulence, flow aeration and threedimensional flow motions. While comprehensive research into hydraulic jumps on smooth bed has improved the understanding of flow aeration and turbulence, limited research has been done of hydraulic jumps on rough bed. Herein novel experiments were conducted in hydraulic jumps on uniformly-distributed bed macro-roughness. Both air-water flow patterns and basic air-water flow properties were investigated. The hydraulic jumps on the rough bed exhibited some remarkable differences compared to smooth bed jumps including some pre-aeration of the flow upstream of the jump, an upwards shift of the jump roller and a clear water flow region underneath the jump. Airwater flow measurements were conducted with a phase-detection probe, showing similar distributions of air-water flow properties for the rough and smooth bed jumps. Comparative analyses highlighted some distinctive effects of the bed roughness including an upwards shift of the hydraulic jump and an increase in bubble count rate and void fractions in the region close to the jump toe. In the second half of the hydraulic jumps the rough bed led to a clear water region with large scale vortices which were advected downstream. The present study highlighted the potential that improved and nonstandard invert designs may have for flow manipulations and design enhancements.

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Section: Free-surface Characteristicssupporting

confidence: 83%

Section: Free-surface Characteristicscontrasting

confidence: 56%

Air–Water Flow Patterns of Hydraulic Jumps on Uniform Beds Macroroughness

Felder

Chanson

2018

J. Hydraul. Eng.

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“…The reliability and accuracy of LES for this study were verified by the computing and experimental results. Similar hydraulic jumps in the stilling basin were observed from the regime of both the test and computation ( Figure 3) in all 3 cases, and the numerical model captured the flow profiles [30] accurately compared with test data (Figure 4) and the differences of the average pressure between test results and calculated results ( Figure 5) were very small except for individual locations in case 3.…”

Section: Verification Of Mathematical Modelsupporting

confidence: 64%

Study on the Best Depth of Stilling Basin with Shallow-Water Cushion

Liao

2018

Water

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The depth of the stilling basin with shallow-water cushion (SBSWC) is a key factor that affects the flow regime of hydraulic jump in the basin. However, the specific depth at which the water cushion is considered as 'shallow' has not been stated clearly by far, and only conceptual description is provided. Therefore, in order to define the best depth of SBSWC and its relationship between the Froude number at the inlet of the stilling basin, a large number of experiments were carried out to investigate SBSWC. First of all, 30 cases including five different Froude numbers and six depths were selected for which large eddy simulation (LES) was firstly verified by the experiments and then adopted to calculate the hydraulic characteristics in the stilling basin. Finally, three standards, based on the flow regime of hydraulic jump, the location of the main stream and the energy dissipation rate, were proposed to define the best depth of SBSWC. The three criteria are as follows: (1) a complete hydraulic jump occurs in the basin (2) the water cushion is about 1/10-1/3 deep of the stilling basin, and (3) the energy dissipation rate is more than 70% and the unit volume energy dissipation rate is as high as possible. It showed that the best depth ratio of SBSWC (depth to length ratio) was between 0.1 and 0.3 and it also indicated the best depth increased with the increase in Froude number. The results of the work are of significance to the design and optimizing of SBSWC.

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“…Their results showed that the tail-water depth, the roller length, and the hydraulic jump length on a gradual expansion basin with the rough bed were significantly smaller than that of the classical hydraulic jumps in a rectangular basin with smooth and rough bed. It should be mentioned that Pagliara and Palermo [23] and Felder and Chanson [24] took into consideration the effect of air concentration, bed roughness and channel slope on both sequent depth ratio and other lengths of HJs occurring on rough beds.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the effects of the air concentration on the hydraulic jump characteristics have been studied. Pagliara and Palermo [23] showed that in a two-phase flow (water and entrained air), locating the water surface is problematic and an equivalent flow depth (d e ) is commonly used. The depth de represents the normal distance from the channel invert reference (effective top ET) to an elevation where the air concentration reaches 90 %.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Hydraulic Jump over Rough Beds

Nikmehr

Aminpour²

2020

Period. Polytech. Civil Eng.

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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.

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Hydraulic jumps on rough and smooth beds: aggregate approach for horizontal and adverse-sloped beds

Cited by 48 publications

References 23 publications

Air–Water Flow Patterns of Hydraulic Jumps on Uniform Beds Macroroughness

Air–Water Flow Patterns of Hydraulic Jumps on Uniform Beds Macroroughness

Study on the Best Depth of Stilling Basin with Shallow-Water Cushion

Numerical Simulation of Hydraulic Jump over Rough Beds

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