Do we understand the bubble formation by a single drop impacting upon liquid surface?

Wang, Anbang; Kuan, Chen-Chi; Tsai, Pei-Hsun

doi:10.1063/1.4822483

Cited by 46 publications

(21 citation statements)

References 25 publications

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“…those with a larger vertical extent. Finally, Wang, Kuan and Tsai [29] have shown that the large bubble entrapment on unrestricted pools also occurs only for prolate drops, and over a wider range of conditions than originally observed [27].…”

Section: Introductionmentioning

confidence: 82%

Vortex-ring-induced large bubble entrainment during drop impact

Thoraval

Thoroddsen

2016

Phys. Rev. E

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For a limited set of impact conditions, a drop impacting onto a pool can entrap an air bubble as large as its own size. The subsequent rise and rupture of this large bubble plays an important role in aerosol formation and gas transport at the air-sea interface. The large bubble is formed when the impact crater closes up near the pool surface and is known to occur only for drops that are prolate at impact. Herein we use experiments and numerical simulations to show that a concentrated vortex ring, produced in the neck between the drop and the pool, controls the crater deformations and pinchoff. However, it is not the strongest vortex rings that are responsible for the large bubbles, as they interact too strongly with the pool surface and self-destruct. Rather, it is somewhat weaker vortices that can deform the deeper craters, which manage to pinch off the large bubbles. These observations also explain why the strongest and most penetrating vortex rings emerging from drop impacts are not produced by oblate drops but by more prolate drop shapes, as had been observed in previous experiments.

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Section: Introductionmentioning

confidence: 82%

Vortex-ring-induced large bubble entrainment during drop impact

Thoraval

Thoroddsen

2016

Phys. Rev. E

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“…form and the oscillations of the impacting drop [20,35,36]. However, since our work is related to the retraction dynamics and the jet and droplet characteristics, the precise shape of the impacting drop and the subsequent geometry of the cavity formed by this impact will not be considered in the present study.…”

Section: Qualitative Studymentioning

confidence: 98%

Jet dynamics post drop impact on a deep pool

2017

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We investigate experimentally the jet formed by the collapse of a cavity created by the impact of a drop on a pool of the same aqueous liquid. We show that jets can emerge with very different shapes and velocities, depending on the impact parameters, thus generating droplets with various initial sizes and velocities. After presenting the jet velocity and top drop radius variation as a function of the impact parameters, we discuss the influence of the liquid parameters on the jet velocity. This allows us to define two different regimes: the singular jet and the cavity jet regimes, where the mechanisms leading to the cavity retraction and subsequent jet dynamics are drastically different. In particular, we demonstrate that in the first regime, a singular capillary wave collapse sparks the whole jet dynamics, making the jet's fast, thin, liquid parameters dependent and barely reproducible. On the contrary, in the cavity jet regime, defined for higher impact Froude numbers, the jets are fat and slow. We show that jet velocity is simply proportional to the capillary velocity √ γ /ρ l D d , where γ is the liquid surface tension, ρ l the liquid density, and D d the impacting drop diameter, and it is in particular independent of viscosity, impact velocity, and gravity, even though the cavity is larger than the capillary length. Finally, we demonstrate that capillary wave collapse and cavity retraction are correlated in the singular regime and decorrelated in the cavity jet regime.

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“…In contrast, for impact on a pool on these small length scales, capillary effects are expected to be much more significant when compared to the impact of millimetresized drops, or even dominating over gravity (Aristoff & Bush 2009). Capillary effects on the small air bubbles resulting from the air-film rupture have been investigated (Bouwhuis et al 2012;Lee et al 2012;Bouwhuis et al 2015;Hendrix et al 2016), but air bubbles due to the collision of surface waves within the cavity (called 'regular bubble entrapment', as described in Pumphrey & Elmore (1990), , Wang et al (2013), Chen & Guo (2014) for millimetre-sized drops) for single impacting microdrops is still ongoing research. Impacting microjets and microdrop trains on liquid pools have not yet been studied in detail.…”

mentioning

confidence: 99%

Impact of a high-speed train of microdrops on a liquid pool

et al. 2016

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A train of high-speed microdrops impacting on a liquid pool can create a very deep and narrow cavity, reaching depths more than 1000 times the size of the individual drops. The impact of such a droplet train is studied numerically using boundary integral simulations. In these simulations, we solve the potential flow in the pool and in the impacting drops, taking into account the influence of liquid inertia, gravity and surface tension. We show that for microdrops the cavity shape and maximum depth primarily depend on the balance of inertia and surface tension and discuss how these are influenced by the spacing between the drops in the train. Finally, we derive simple scaling laws for the cavity depth and width.

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Do we understand the bubble formation by a single drop impacting upon liquid surface?

Cited by 46 publications

References 25 publications

Vortex-ring-induced large bubble entrainment during drop impact

Vortex-ring-induced large bubble entrainment during drop impact

Jet dynamics post drop impact on a deep pool

Impact of a high-speed train of microdrops on a liquid pool

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