Air–water interface dynamic and free surface features in hydraulic jumps

Murzyn, Frédéric; Mouazé, Dominique; Chaplin, J.R.

doi:10.1080/00221686.2007.9521804

Cited by 67 publications

(41 citation statements)

References 17 publications

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“…Chanson (1995) highlighted the presence of a local maximum void fraction in the shear layer of hydraulic jumps with partially-developed inflow: that is, when the upstream flow is not fully-developed and turbulent boundary layer does not extend up to the free-surface. Chanson and Brattberg (2000) and Murzyn et al (2005Murzyn et al ( ,2007 showed some seminal bubbly flow features in steady and weak hydraulic jumps respectively. Turbulence measurements in hydraulic jumps were conducted also by Rouse et al (1959), Liu et al (2004), Chanson (2007) and Kucukali and Chanson (2008), although the first study was conducted in a wind tunnel, and the second was restricted to low Froude numbers (Fr 1 < 3.3).…”

Section: Introductionmentioning

confidence: 99%

Bubbly Two-Phase Flow in Hydraulic Jumps at Large Froude Numbers

Chanson

2011

J. Hydraul. Eng.

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A hydraulic jump is a sudden rapid transition from a super-to a sub-critical flow. At large inflow Froude numbers, the jump is characterised by a significant amount of entrained air. Herein the bubbly twophase flow properties of steady and strong hydraulic jumps were investigated experimentally. The results demonstrate the strong air entrainment rate, and the depth-averaged void fraction data highlight a rapid deaeration of the jump roller. The results suggest that the hydraulic jumps are effective aerators and that the rate of detrainment is comparatively smaller at the largest Froude numbers.

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Section: Introductionmentioning

confidence: 99%

Bubbly Two-Phase Flow in Hydraulic Jumps at Large Froude Numbers

Chanson

2011

J. Hydraul. Eng.

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“…The results showed that the bore front arrival time, bore height, bore celerity... were basically identical. Small differences were observed linked to the fluctuating nature of the bore roller free-surface, as observed in stationary hydraulic jumps and breaking bores (MOUAZE et al 2005, MURZYN et al 2007, LENG and CHANSON 2015b.…”

Section: Data Accuracymentioning

confidence: 99%

Coupling between free-surface fluctuations, velocity fluctuations and turbulent Reynolds stresses during the upstream propagation of positive surges, bores and compression waves

Leng

Chanson

2015

Environ Fluid Mech

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In open channel, canals and rivers, a rapid increase in flow depth will induce a positive surge, also called bore or compression wave. The positive surge is a translating hydraulic jump. Herein new experiments were conducted in a large-size rectangular channel to characterise the unsteady turbulent properties, including the coupling between free-surface and velocity fluctuations. Experiments were repeated 25 times and the data analyses yielded the instantaneous median and instantaneous fluctuations of free-surface elevation, velocities and turbulent Reynolds stresses. The passage of the surge front was associated with large free-surface fluctuations, comparable to those observed in stationary hydraulic jumps, coupled with large instantaneous velocity fluctuations. The bore propagation was associated with large turbulent Reynolds stresses and instantaneous shear stress fluctuations, during the passage of the surge. A broad range of shear stress levels was observed underneath the bore front, with the probability density of the tangential stresses distributed normally and the normal stresses distributed in a skewed single-mode fashion. Maxima in normal and tangential stresses were observed shortly after the passage of a breaking bore roller toe. The maximum Reynolds stresses occurred after the occurrence of the maximum free-surface fluctuations, and this time lag implied some interaction between the free-surface fluctuations and shear stress fluctuations beneath the surge front, and possibly some causal effect.

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“…The location of the mean free surface and its fluctuations in this type of flows, as well as the role that the turbulent structures have on it, has been studied under different conditions [18,22,20]. Experimental observations reveal that in strong turbulent breakers (such as those found in large hydraulic jumps) the collapse of the free surface is the leading mechanism of air entrainment.…”

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confidence: 99%

Dynamics of large turbulent structures in a steady breaker

Rodríguez-Rodríguez

Marugán-Cruz

Aliseda

et al. 2011

Experimental Thermal and Fluid Science

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a b s t r a c tThe flow near the leading edge of a steady breaker has been studied experimentally using Bubble Image Velocimetry (BIV) with the aim of characterizing the dynamics of the large eddies responsible for air entrainment. It is well reported in the literature, and confirmed by our measurements of the instanta neous velocity field, that this flow shares some important features with the turbulent shear layer formed between two parallel semi infinite streams with different velocities. Namely, the formation of a periodic array of coherent vortices, the constant convective velocity of those vortices, the linear relation between their size and their downstream position and the self similar structure of both mean velocity profiles and Reynolds shear stresses. Nonetheless, important differences exists between the dynamics of the large eddies in a steady breaker and those in a free shear layer. Particularly, the convective velocity of these large structures is slower in a steady breaker and, consistent with this, their growth rates are larger. A physical interpretation of these differences is provided together with a discussion of their implications. To support our measurements and conclusions, we present a careful analysis of the accuracy of the BIV technique in turbulent flows with large bubbles.

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Air–water interface dynamic and free surface features in hydraulic jumps

Cited by 67 publications

References 17 publications

Bubbly Two-Phase Flow in Hydraulic Jumps at Large Froude Numbers

Bubbly Two-Phase Flow in Hydraulic Jumps at Large Froude Numbers

Coupling between free-surface fluctuations, velocity fluctuations and turbulent Reynolds stresses during the upstream propagation of positive surges, bores and compression waves

Dynamics of large turbulent structures in a steady breaker

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