The inner world of a collapsing bubble

Supponen, Outi; Kobel, Philippe; Obreschkow, Danail; Farhat, Mohamed

doi:10.1063/1.4931098

Cited by 71 publications

(31 citation statements)

References 8 publications

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“…A bubble collapsing near a free surface has experimentally been studied by Supponen et al 13,14 through high-speed imaging. In the experiment (details of the setup in 14 ), a spherical cavitation bubble is created in water contained in a cubic (18×18×18 cm³) test chamber using a green, highpower laser pulse (wavelength 532 nm, duration 8 ns).…”

Section: Experimental Set-upmentioning

confidence: 99%

“…-Other geometric features of the bubble evolution (quantitative), that can be directly compared to the simulation, such as the jet diameter, maximum bubble radius etc. The high-speed movies extracted from the experiment 13 have a resolution of 400x250pixels, with a scale of 17pixels corresponding to 1mm, so bubble dimensions can be derived.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of bubble expansion and collapse in the vicinity of a free surface

et al. 2016

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The present paper focuses on the numerical simulation of the interaction of laser-generated bubbles with a free surface, including comparison of the results with instances from high-speed videos of the experiment. The Volume Of Fluid (VOF) method was employed for tracking liquid and gas phases, while compressibility effects were introduced with appropriate equations of state for each phase. Initial conditions of the bubble pressure were estimated through the traditional Rayleigh Plesset equation. The simulated bubble expands in a non-spherically symmetric way, due to the interference of the free surface, obtaining an oval shape at the maximum size. During collapse a jet with mushroom cap is formed at the axis of symmetry, with the same direction as the gravity vector, which splits the initial bubble to an agglomeration of toroidal structures. Overall, the simulation results are in agreement with the experimental images, both quantitatively and qualitatively, while pressure waves are predicted both during the expansion and the collapse of the bubble. Minor discrepancies in the jet velocity and collapse rate are found and are attributed to the thermodynamic closure of the gas inside the bubble.

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Section: Experimental Set-upmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simulation of bubble expansion and collapse in the vicinity of a free surface

et al. 2016

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“…The following energy release leads to shock waves and temperature peaks in the area near the collapsing bubbles [1,6,7]. These effects lead to grain refinement of aluminum primarily via (1) wetting of nonsoluble and nonmetallic particles in the melt (e.g., Al 2 O 3 ) [8][9][10][11], (2) nucleation of aluminum grains caused by the collapse accompanying shock waves [11][12][13][14][15], (3) dendrite fragmentation [1,9,[16][17][18][19][20], and (4) de-agglomeration [1,21]. In addition, UST can be used for melt degassing to further increase the density index and improve both the melt and final casting quality.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Ultrasonic Induced Cavitation and Acoustic Streaming in Liquid and Solidifying Aluminum

Riedel

Liepe

Scharf

2020

Metals

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Ultrasonic treatment (UST), more precisely, cavitation and acoustic streaming, of liquid light metal alloys is a very promising technology for achieving grain and structure refinement, and therefore, better mechanical properties. The possibility of predicting these process phenomena is an important requirement for understanding, implementing, and scaling this technology in the foundry industry. Using an established (casting) computational fluid dynamics (CFD)-simulation tool, we studied the ability of this software to calculate the onset and expansion of cavitation and acoustic streaming for the aluminum alloy A356, partly depending on different radiator geometries. A key aspect was a holistic approach toward pressure distribution, cavitation, and acoustic streaming prediction, and the possibility of two- and (more importantly) three-dimensional result outputs. Our feasibility analysis showed that the simulation tool is able to predict the mentioned effects and that the results obtained are in good agreement with the results and descriptions of previous investigations. Finally, capabilities and limitations as well as future challenges for further developments are discussed.

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“…In the past few decades, a large amount of works have been undertaken to understand the characteristics of bubble collapse [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Lauterborn recorded the process of a single bubble collapsing near a rigid wall, in which the shock wave emission was captured by a schlieren system [25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Collapse of Multiple Bubbles and the Energy Conversion during Bubble Collapse

Zhang

Deng

2019

Water

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This paper investigates numerically the collapses of both a single cavitation bubble and a cluster consisting of 8 bubbles, concerning mainly on the conversions between different forms of energy. Direct numerical simulation (DNS) with volume of fluid (VOF) method is applied, considering the detailed resolution of the vapor-liquid interfaces. First, for a single bubble near a solid wall, we find that the peak value of the wave energy, or equivalently the energy conversion rate decreases when the distance between the bubble and the wall is reduced. However, for the collapses of multiple bubbles, this relationship between the bubble-wall distance and the conversion rate reverses, implying a distinct physical mechanism. The evolutions of individual bubbles during the collapses of multiple bubbles are examined. We observe that when the bubbles are placed far away from the solid wall, the jetting flows induced by all bubbles point towards the cluster centre, while the focal point shifts towards the solid wall when the cluster is very close to the wall. We note that it is very challenging to consider thermal and acoustic damping mechanisms in the current numerical methods, which might be significant contributions to the energy budget, and we leave it open to the future studies.

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The inner world of a collapsing bubble

Cited by 71 publications

References 8 publications

Simulation of bubble expansion and collapse in the vicinity of a free surface

Simulation of bubble expansion and collapse in the vicinity of a free surface

Simulation of Ultrasonic Induced Cavitation and Acoustic Streaming in Liquid and Solidifying Aluminum

Numerical Study of the Collapse of Multiple Bubbles and the Energy Conversion during Bubble Collapse

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