Velocity Distribution and Attenuation Characteristics in F Jumps on Rough Beds

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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Velocity Distribution and Attenuation Characteristic in Hydraulic Jumps on Rough Beds

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2019-0536 ◽

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.

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Retraction: Velocity distribution and attenuation characteristic in hydraulic jumps on rough beds (cjce-2019-0536)

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2021-0573 ◽

2021 ◽

pp. 1-1

Keyword(s):

Velocity Distribution ◽

Hydraulic Jumps ◽

Attenuation Characteristic ◽

Rough Beds

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Dynamics of comets in the collapsing protosolar nebula

International Astronomical Union Colloquium ◽

10.1017/s0252921100031225 ◽

1999 ◽

Vol 173 ◽

pp. 45-50

Author(s):

L. Neslušan

Keyword(s):

Solar System ◽

Velocity Distribution ◽

Oort Cloud ◽

Interstellar Clouds ◽

Protosolar Nebula ◽

Moving Bodies

AbstractComets are created in the cool, dense regions of interstellar clouds. These macroscopic bodies take place in the collapse of protostar cloud as mechanically moving bodies in contrast to the gas and miscroscopic dust holding the laws of hydrodynamics. In the presented contribution, there is given an evidence concerning the Solar system comets: if the velocity distribution of comets before the collapse was similar to that in the Oort cloud at the present, then the comets remained at large cloud-centric distances. Hence, the comets in the solar Oort cloud represent a relict of the nebular stage of the Solar system.

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