Numerical and experimental investigation into the dynamics of a bubble-free-surface system

Bempedelis, Nikolaos; Zhou, Jiayi; Andersson, Mats; Ventikos, Yiannis

doi:10.1103/physrevfluids.6.013606

Cited by 18 publications

(16 citation statements)

References 47 publications

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“…These measurements are the same ones presented in figure 12, taken using a second camera (simultaneously) set with a lower temporal resolution and an extended temporal window. The images show how the shape of the upward jet also depends significantly on the inception depth of the cavity, as reported by Chen et al (2013), Li et al (2019) and Bempedelis et al (2021).…”

supporting

confidence: 79%

“…Thin liquid sheets that atomise into a mist may also be induced from oscillating vapour bubbles near a free surface. These cavitation bubbles can be created by an electrical discharge (Li et al 2019;Phan, Nguyen & Park 2020), or by the dielectric rupture of the liquid provoked by a high-power focused laser pulse (Gregorčič, Petkovšek & Možina 2007;Chen et al 2013;Patrascioiu et al 2014;Koukouvinis et al 2016;Supponen et al 2016;Jalaal et al 2019;Bempedelis et al 2021). Those studies discuss the dynamics of cavities produced at different distances below the liquid level, and also the formation of an upward liquid jet rising from the surface after the cavity collapse (Blake & Gibson 1987;Robinson et al 2001;Pearson et al 2004;Li et al 2019;Saade et al 2021).…”

Section: Introductionmentioning

confidence: 99%

“…2019; Bempedelis et al. 2021). Those studies discuss the dynamics of cavities produced at different distances below the liquid level, and also the formation of an upward liquid jet rising from the surface after the cavity collapse (Blake & Gibson 1987; Robinson et al.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of pulsed laser-induced cavities on a liquid–gas interface: from a conical splash to a ‘bullet’ jet

2022

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The inception of a cavitation bubble in a liquid by focusing a short and intense laser pulse near its free surface develops not only an upwards directed jet, but a second jet of opposite direction into the bulk liquid. When the laser is focused a few microns below the surface, the rapid deposition of energy produces a splash, whose later sealing gives origin to two particularly elongated opposing jets. Interestingly, the evolution of the downward jet flowing into the liquid pool has many similarities to that observed in free water entry experiments, e.g. the creation of a slender and stable cavity in the liquid. The downward jet can reach speeds of up to $40$ m s $^{-1}$ and travels distances of more than 15 times the maximum radius of the laser induced cavity before losing momentum. The longer lifetime of this so-called ‘bullet’ jet as compared with conventional cavitation based jets, the alignment of the jet perpendicular to the free surface and the possibility of scaling the phenomenon opens up potential applications when generated on small droplets or in shallow liquids. In this work, the underlying mechanisms behind the formation of the bullet jets are initially investigated by performing a set of experiments designed to address specific questions about the phenomenon under study. Those were followed by numerical simulations used to give a quantitative and detailed explanation to the experimental observations.

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supporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

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Dynamics of pulsed laser-induced cavities on a liquid–gas interface: from a conical splash to a ‘bullet’ jet

2022

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“…2019; Bempedelis et al. 2021), shows that the eventual crown formation after the central jet has formed is correlated with the second expansion of the bubble and the induced outward flow. However, since the shock wave is emitted at the same time, it is difficult to disentangle these two effects and come to any conclusions on the origin of crown formation.…”

Section: Phenomenologymentioning

confidence: 99%

“…2019 a , b ; Serra & Piqué 2019; Bempedelis et al. 2021). Figure 1 shows a typical sequence of events observed in a laboratory experiment related to the LIFT process: due to optical/thermal breakdown via focusing of a pulsed laser, a bubble nucleates, expands and collapses while a jet is ejected upwards from the free surface.…”

Section: Introductionmentioning

confidence: 99%

Crown formation from a cavitating bubble close to a free surface

et al. 2021

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A rapidly growing bubble close to a free surface induces jetting: a central jet protruding outwards and a crown surrounding it at later stages. While the formation mechanism of the central jet is known and documented, that of the crown remains unsettled. We perform axisymmetric simulations of the problem using the free software program BASILISK, where a finite-volume compressible solver has been implemented, which uses a geometric volume-of-fluid (VoF) method for the tracking of the interface. We show that the mechanism of crown formation is a combination of a pressure distortion over the curved interface, inducing flow focusing, and of a flow reversal, caused by the second expansion of the toroidal bubble that drives the crown. The work culminates in a parametric study with the Weber number, the Reynolds number, the pressure ratio and the dimensionless bubble distance to the free surface as control parameters. Their effects on both the central jet and the crown are explored. For high Weber numbers, we observe the formation of weaker ‘secondary crowns’, highly correlated with the third oscillation cycle of the bubble.

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An analysis of surface breakup induced by laser-generated cavitation bubbles in a turbulent liquid jet

Zhou

Andersson

2020

Exp Fluids

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The breakup of turbulent liquid jets by cavitation bubbles was investigated by artificially introducing them by focusing laser light into the jet. The induced surface deformations and ejected liquid structures were characterized using shadowgraphy with a high-speed video camera. The flow velocity of the liquid jets, which were ejected from a 6 mm nozzle, was varied by adjusting the injection pressure from 1 to 5 bar. Deionized water and a dipropylene glycol–water mixture were used to compare the breakup of liquid jets with different surface tension and viscosity. Surface deformation and breakup were found to occur in two stages. One was early breakup of liquid strings into tiny droplets. This was followed by the formation of a larger structure separating into ligaments and larger drops. Averaged time-resolved one-dimensional plots were introduced and implemented to analyze breakup statistically, to address the problem of shot-to-shot variations in the breakup due to the turbulent condition of the jets. Bubble-induced breakup could easily be distinguished from spontaneous breakup with this method. Both the position of bubble formation and the injection pressure had an influence on the scale of the breakup. The deformation of the jet surface was highly affected by shear. The structure of the deformation became less intact when the surface tension was lower. The sizes of the drops produced during the second stage of breakup were analyzed. The bubble-induced breakup produced smaller drops than the spontaneous breakup at lower injection pressure. As expected, lower surface tension favored droplet detachment and smaller sized drops. Graphic abstract

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Numerical and experimental investigation into the dynamics of a bubble-free-surface system

Cited by 18 publications

References 47 publications

Dynamics of pulsed laser-induced cavities on a liquid–gas interface: from a conical splash to a ‘bullet’ jet

Dynamics of pulsed laser-induced cavities on a liquid–gas interface: from a conical splash to a ‘bullet’ jet

Crown formation from a cavitating bubble close to a free surface

An analysis of surface breakup induced by laser-generated cavitation bubbles in a turbulent liquid jet

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