Particle tracking velocimetry of the flow field around a collapsing cavitation bubble

Kröninger, Dennis; Köhler, Karsten; Kurz, Thomas; Lauterborn, Werner

doi:10.1007/s00348-009-0743-1

Cited by 62 publications

(48 citation statements)

References 40 publications

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“…Finally, it is interesting to note that, in contrast to reports demonstrating bubble formation in liquids due to laser absorption [2][3][4][5][6][7][8][9][10][11][12], our results were obtained using a low power (<70 mW) CW laser diode. While we have observed in our experiments bubbles with lifetimes ranging from seconds to minutes, cavitation and nucleation generated bubbles have an average lifetime of micro or milliseconds.…”

Section: Introductioncontrasting

confidence: 60%

“…1vetuasaber@ciencias.unam.mx 2jhcordero@iim.unam.mx Bubbles can be generated optically trough optical breakdown in liquids (cavitation effects) with laser light; this process usually involves high-power pulsed laser sources [2][3][4][5][6][7][8][9][10][11][12]. The interaction of a short laser pulse with absorbing liquids or solid materials in contact with liquid is central to a number of applications, including laser cleaning, pulsed laser deposition of thin film materials, laser tissue removal, selective cell killing and bubble jet printer technologies.…”

Section: Introductionmentioning

confidence: 99%

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Nanoparticle coated optical fibers for single microbubble generation

Pimentel‐Domínguez

Hernández‐Cordero

2011

SPIE Proceedings

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The study of bubbles and bubbly flows is important in various fields such as physics, chemistry, medicine, geophysics, and even the food industry. A wide variety of mechanical and acoustic techniques have been reported for bubble generation. Although a single bubble may be generated with these techniques, controlling the size and the mean lifetime of the bubble remains a difficult task. Most of the optical methods for generation of microbubbles involve high-power pulsed laser sources focused in absorbing media such as liquids or particle solutions. With these techniques, single micron-sized bubbles can be generated with typical mean lifetimes ranging from nano to microseconds. The main problem with these bubbles is their abrupt implosion: this produces a shock wave that can potentially produce damages on the surroundings. These effects have to be carefully controlled in biological applications and in laser surgery, but thus far, not many options are available to effectively control micron-size bubble growth. In this paper, we present a new technique to generate microbubbles in non-absorbing liquids. In contrast to previous reports, the proposed technique uses low-power and a CW radiation from a laser diode. The laser light is guided through an optical fiber whose output end has been coated with nanostructures. Upon immersing the tip of the fiber in ethanol or water, micron-size bubbles can be readily generated. With this technique, bubble growth can be controlled through adjustments on the laser power. We have obtained micron-sized bubbles with mean lifetimes in the range of seconds. Furthermore, the generated bubbles do not implode, as verified with a high-speed camera and flow visualization techniques.

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Section: Introductioncontrasting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Nanoparticle coated optical fibers for single microbubble generation

Pimentel‐Domínguez

Hernández‐Cordero

2011

SPIE Proceedings

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“…As regards the formation of the vortex flow, the exact mechanism is not fully clear, but the jet impact and penetration of the distant bubble wall and the resulting high velocity gradients play a crucial role. As the bubble collapses aspherically and the jet impinges the opposite bubble wall, abruptly a region of high pressure is formed and flows of opposite direction are created [33] [34]. Since it is known that the maximum jet speed should even increase with ߛ up to about ߛ = 3.6 [32], it follows that the local vorticity generated during bubble collapse is still considerable for larger stand-offs, while the overall vorticity is expected to decrease as the jet volume decreases for large ߛ by roughly 1/ߛ ଶ [35].…”

Section: High Speed Observations Of Bubble Dynamics and Particle Detamentioning

confidence: 99%

“…Furthermore we remark that shock waves could not be resolved in the experiment, but several shocks should be generated during the torus collapse at the substrate (see e.g. the images in [33][40]).…”

Section: Small ߛmentioning

confidence: 99%

Mechanisms of single bubble cleaning

Reuter

Mettin

2016

Ultrasonics Sonochemistry

117

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The dynamics of collapsing bubbles close to a flat solid is investigated with respect to its potential for removal of surface attached particles. Individual bubbles are created by nanosecond Nd:YAG laser pulses focused into water close to glass plates contaminated with melamine resin micro-particles. The bubble dynamics is analysed by means of synchronous high-speed recordings. Due to the close solid boundary, the bubble collapses with the well-known liquid jet phenomenon. Subsequent microscopic inspection of the substrates reveals circular areas clean of particles after a single bubble generation and collapse event. The detailed bubble dynamics, as well as the cleaned area size, is characterised by the non-dimensional bubble stand-off γ=d/Rmax, with d: laser focus distance to the solid boundary, and Rmax: maximum bubble radius before collapse. We observe a maximum of clean area at γ≈0.7, a roughly linear decay of the cleaned circle radius for increasing γ, and no cleaning for γ>3.5. As the main mechanism for particle removal, rapid flows at the boundary are identified. Three different cleaning regimes are discussed in relation to γ: (I) For large stand-off, 1.8<γ<3.5, bubble collapse induced vortex flows touch down onto the substrate and remove particles without significant contact of the gas phase. (II) For small distances, γ<1.1, the bubble is in direct contact with the solid. Fast liquid flows at the substrate are driven by the jet impact with its subsequent radial spreading, and by the liquid following the motion of the collapsing and rebounding bubble wall. Both flows remove particles. Their relative timing, which depends sensitively on the exact γ, appears to determine the extension of the area with forces large enough to cause particle detachment. (III) At intermediate stand-off, 1.1<γ<1.8, only the second bubble collapse touches the substrate, but acts with cleaning mechanisms similar to an effective small γ collapse: particles are removed by the jet flow and the flow induced by the bubble wall oscillation. Furthermore, the observations reveal that the extent of direct bubble gas phase contact to the solid is partially smaller than the cleaned area, and it is concluded that three-phase contact line motion is not a major cause of particle removal. Finally, we find a relation of cleaning area vs. stand-off γ that deviates from literature data on surface erosion. This indicates that different effects are responsible for particle removal and for substrate damage. It is suggested that a trade-off of cleaning potential and damage risk for sensible surfaces might be achieved by optimising γ.

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“…The velocity vectors of the liquid around the bubble are all directed to a point near the center of the bubble, and a liquid jet is starting to form at the right of the bubble, which side is far from the rigid boundary. Kroninger et al 25 get the similar experimental and numerical vector graph. The liquid jet will penetrate the bubble and impinge on the rigid boundary at last.…”

Section: Liquid Jet Generated During Bubble Collapsementioning

confidence: 74%

The collapse of a bubble against infinite and finite rigid boundaries for underwater laser propulsion

Chen

Han

et al. 2011

Journal of Applied Physics

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In order to investigate the influence of a bubble on underwater laser propulsion, the analytical formula of the bubble collapse time near rigid boundary is deduced from Rayleigh collapse time and Rattray prolongation factor. Experiments and numerical simulations are employed to validate the collapse time formula. The collapsing features of a bubble, including the maximum bubble radius Rmax, the collapse time of the bubble TCR, the shock wave and liquid jet emitted during the bubble collapse, are obtained near infinite and finite rigid boundaries. The theoretical, numerical and experimental results for the dimensionless distance γ > 1 all illuminate that TCR increases with Rmax near the rigid boundary. Rmax and TCR increase with the laser energy first, then begin to level out as the laser energy continues to increase, thus it is impossible to increase the propelling force just through increasing the laser pulse energy continuously. In addition, TCR is smaller, and the shock wave pressure and the liquid jet velocity are larger near the finite rigid boundary than that near the infinite rigid boundary, which means that the bubble collapses fiercer in the former case, in other words the finite rigid boundary gets more propelling force.

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Particle tracking velocimetry of the flow field around a collapsing cavitation bubble

Cited by 62 publications

References 40 publications

Nanoparticle coated optical fibers for single microbubble generation

Nanoparticle coated optical fibers for single microbubble generation

Mechanisms of single bubble cleaning

The collapse of a bubble against infinite and finite rigid boundaries for underwater laser propulsion

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