Explosions at the water surface

Benusiglio, Adrien; Quéré, David; Clanet, Christophe

doi:10.1017/jfm.2014.255

Cited by 18 publications

(11 citation statements)

References 28 publications

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“…Interestingly, we find that the growth of the bubbles at early times follows a power‐law relation h ∼ t α with α = 0.62 ± 0.01 (Figure a). In comparison, the bubbles created by 3D explosion in liquids shows a scaling R ∼ t 2/5 , where R is the radius of explosion bubbles at early times . The growth of explosion bubbles in quasi‐2D granular bed has also been studied previously using explosive black powders, where an exponential growth with R ∼ [1 − exp(− t / τ )] has been proposed .…”

Section: Resultsmentioning

confidence: 95%

Dynamics and scaling of explosion cratering in granular media

et al. 2018

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Granular cratering is a ubiquitous phenomenon occurring in various natural and industrial contexts. Although impactinduced granular cratering has been extensively studied, fewer experiments have been conducted on granular cratering via low-energy explosions. Here, we study the dynamics and scaling of explosion granular cratering by injecting short pulses of pressurized air in quasi-two-dimensional granular media. Through an analysis of the dynamics of explosion processes at different explosion pressures, explosion durations, and burial depths, we identify two regimes, the bubbling and the eruption regimes, in explosion granular cratering. Our experiments explore the distinctive dynamics and crater morphologies of these regimes and show the energy scaling of the size of explosion craters. We compare high-energy and low-energy explosion cratering as well as explosion and impact cratering in terms of their energy scalings. Our work illustrates complex granular flows in explosion cratering and provides new insights into the general scaling of granular cratering processes. The burial depth is fixed at d b 5 3.2 cm. The dashed line indicates a power-law scaling V b~E 1.2 . [Color figure can be viewed at wileyonlinelibrary.com.] 8

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Section: Resultsmentioning

confidence: 95%

Dynamics and scaling of explosion cratering in granular media

et al. 2018

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“…On the other hand, when a cavity is larger than a few centimeters, the relaxation process is a priori gravity driven since capillarity should become irrelevant [31,32]. In our drop impact experiments, typical cavity dimensions (heights H and widths 2R) range from 5 to 15 mm, so that both gravity and capillarity might play a role in the relaxation process.…”

Section: Qualitative Studymentioning

confidence: 89%

“…While jet dynamics and droplet ejection have been characterized for the collapse of cavities obtained by the bursting of bubbles [23,29,30] or large interface deformation [31,32], ours is a systematic study of cavities induced by drop impacts. In particular, in this configuration, the shape of the cavity is different, but above all, the cavity sizes are different, intermediate, typically between what has been studied so far, and we will see that this changes the subsequent jet dynamics.…”

Section: Introductionmentioning

confidence: 99%

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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“…It is interesting to note that explosions at the free surface of water [34] exhibited the same scaling exponent for maximum cavity size versus energy, i.e., R max ∼ E 1/4 0 , as for impact cratering. However, in the granular bed, we found R max ∝ (m − m o ) 0.30 ∼ E 0.3 0 as found in large-scale events.…”

Section: Early Cavity Growthmentioning

confidence: 95%

“…In Ref. [34], the early cavity growth produced by an explosion at the water surface was described with a potential flow model simplifying to the expression for the radius R 3Ṙ2 = E 0 /ρ, which easily yields the result R(t) ∝ t 2/5 (here we used indistinctly R cav = R). This 2/5 scaling law was established by Taylor for shock wave propagation following a nuclear blast [35], and it was also found during excitation of hard spheres by examining the growth rate of particle collisions in 2D and half-space simulations [36].…”

Section: Early Cavity Growthmentioning

confidence: 99%

Craters produced by explosions in a granular medium

2017

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We report on an experimental investigation of craters generated by explosions at the surface of a model granular bed. Following the initial blast, a pressure wave propagates through the bed, producing high-speed ejecta of grains and ultimately a crater. We analyzed the crater morphology in the context of large-scale explosions and other cratering processes. The process was analyzed in the context of large-scale explosions, and the crater morphology was compared with those resulting from other cratering processes in the same energy range. From this comparison, we deduce that craters formed through different mechanisms can exhibit fine surface features depending on their origin, at least at the laboratory scale. Moreover, unlike laboratory-scale craters produced by the impact of dense spheres, the diameter and depth do not follow a 1/4-power-law scaling with energy, rather the exponent observed herein is approximately 0.30, as has also been found in large-scale events. Regarding the ejecta curtain of grains, its expansion obeys the same time dependence followed by shock waves produced by underground explosions. Finally, from experiments in a two-dimensional system, the early cavity growth is analyzed and compared to a recent study on explosions at the surface of water.

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Explosions at the water surface

Cited by 18 publications

References 28 publications

Dynamics and scaling of explosion cratering in granular media

Dynamics and scaling of explosion cratering in granular media

Jet dynamics post drop impact on a deep pool

Craters produced by explosions in a granular medium

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