Sonoluminescing bubbles and mass diffusion

Löfstedt, Ritva; Weninger, Keith; Putterman, Seth; Barber, Bradley P.

doi:10.1103/physreve.51.4400

Cited by 134 publications

(128 citation statements)

References 28 publications

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“…The first contribution in this regard was made in the original paper of Gaitan et al (1992), which demonstrated that the radius of the bubble as a function of time observed experimentally exhibits the same behavior as solutions to the Rayleigh-Plesset equation (to be derived in Sec. II); subsequently, studies by Lö fstedt et al (1993Lö fstedt et al ( , 1995 confirmed and elaborated on this conclusion. The Rayleigh-Plesset theory is remarkably simple, and it captures many important features of single-bubble sonoluminescence.…”

Section: Historical Overviewsupporting

confidence: 49%

“…Lö fstedt et al (1995) pointed out that a sonoluminescing bubble cannot possibly be in diffusive equilibrium for these parameters and postulated another ''anomalous mass flow,'' whose mechanism would be ''the key to SL in a single bubble. ''…”

Section: Historical Overviewmentioning

confidence: 99%

“…Since equations with different lead to similar results, one solution to this problem is to delete all the prefactors in parentheses containing Ṙ /c. We thus arrive at a popular form in the context of sonoluminescence (see, for example, Lö fstedt et al, 1995;Barber et al, 1997),…”

Section: B Extensions Of the Rayleigh-plesset Equationmentioning

confidence: 99%

“…To account for these discrepancies to classical bubble dynamics, proposed that the extra mass-ejection mechanism of Lö fstedt et al (1995) is of a chemical nature. The gas in the bubble is hot enough upon collapse to allow for significant dissociation of N 2 and O 2 .…”

Section: Historical Overviewmentioning

confidence: 99%

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Single-bubble sonoluminescence

2002

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Single-bubble sonoluminescence occurs when an acoustically trapped and periodically driven gas bubble collapses so strongly that the energy focusing at collapse leads to light emission. Detailed experiments have demonstrated the unique properties of this system: the spectrum of the emitted light tends to peak in the ultraviolet and depends strongly on the type of gas dissolved in the liquid; small amounts of trace noble gases or other impurities can dramatically change the amount of light emission, which is also affected by small changes in other operating parameters (mainly forcing pressure, dissolved gas concentration, and liquid temperature). This article reviews experimental and theoretical efforts to understand this phenomenon. The currently available information favors a description of sonoluminescence caused by adiabatic heating of the bubble at collapse, leading to partial ionization of the gas inside the bubble and to thermal emission such as bremsstrahlung. After a brief historical review, the authors survey the major areas of research: Section II describes the classical theory of bubble dynamics, as developed by Rayleigh, Plesset, Prosperetti, and others, while Sec. III describes research on the gas dynamics inside the bubble. Shock waves inside the bubble do not seem to play a prominent role in the process. Section IV discusses the hydrodynamic and chemical stability of the bubble. Stable single-bubble sonoluminescence requires that the bubble be shape stable and diffusively stable, and, together with an energy focusing condition, this fixes the parameter space where light emission occurs. Section V describes experiments and models addressing the origin of the light emission. The final section presents an overview of what is known, and outlines some directions for future research. CONTENTS

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Section: Historical Overviewsupporting

confidence: 49%

Section: Historical Overviewmentioning

confidence: 99%

Section: B Extensions Of the Rayleigh-plesset Equationmentioning

confidence: 99%

Section: Historical Overviewmentioning

confidence: 99%

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Single-bubble sonoluminescence

2002

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“…[1][2][3][4][5][6][7][8] Here, P a is the forcing pressure amplitude and /2 the frequency of the forcing field. This phenomenon is called single bubble sonoluminescence ͑SL͒.…”

Section: Introduction a The Phenomenonmentioning

confidence: 99%

Phase diagrams for sonoluminescing bubbles

Lohse

Brenner

Hilgenfeldt

1996

The Journal of the Acoustical Society of America

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Sound driven gas bubbles in water can emit light pulses. This phenomenon is called sonoluminescence ͑SL͒. Two different phases of single bubble SL have been proposed: diffusively stable and diffusively unstable SL. We present phase diagrams in the gas concentration versus forcing pressure state space and also in the ambient radius versus gas concentration and versus forcing pressure state spaces. These phase diagrams are based on the thresholds for energy focusing in the bubble and two kinds of instabilities, namely ͑i͒ shape instabilities and ͑ii͒ diffusive instabilities. Stable SL only occurs in a tiny parameter window of large forcing pressure amplitude P a ϳ1.2-1.5 atm and low gas concentration of less than 0.4% of the saturation. The upper concentration threshold becomes smaller with increased forcing. Our results quantitatively agree with experimental results of Putterman's UCLA group on argon, but not on air. However, air bubbles and other gas mixtures can also successfully be treated in this approach if in addition ͑iii͒ chemical instabilities are considered. All statements are based on the Rayleigh-Plesset ODE approximation of the bubble dynamics, extended in an adiabatic approximation to include mass diffusion effects. This approximation is the only way to explore considerable portions of parameter space, as solving the full PDEs is numerically too expensive. Therefore, we checked the adiabatic approximation by comparison with the full numerical solution of the advection diffusion PDE and find good agreement.

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Mechanistic approach to enhancement of the yield of a sonochemical reaction

2007

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in Wiley InterScience (www.interscience.wiley.com).In this study, a mechanistic approach has been taken to enhance yield of a sonochemical reaction. Formation of highly reactive free radicals due to the transient collapse of cavitation bubbles is the primary mechanism of a sonochemical reaction. A physical (reduction in dissolved gas concentration) and a chemical (increasing the reactant concentration) technique is used for enhancing yield of a sonochemical reaction using those techniques, which influence the phenomenon of radical formation by the cavitation bubbles. A bubble dynamics model is used for explaining the sonochemical phenomena. In a degassed medium, the ultrasound wave undergoes lesser attenuation; moreover, equilibrium size of a bubble shrinks due to rectified diffusion. Because of this, a bubble undergoes more violent collapse, resulting in greater production of radicals that give higher yield. On the other hand, increasing the initial reactant concentration shows an adverse effect on the sonochemical yield. This is ascribed to reduction in water vapor flux in the bubble due to reduction of vapor pressure of the medium. This study, therefore, demonstrates as how macroscopic manifestation (the sonochemical yield) of the microscopic phenomena (transient collapse of cavitation bubble) is a complicated function of several physical processes. The results of this study shed light on the complex and multifaceted physical mechanism of a sonochemical reaction, which may be useful in maximization of yield of other sonochemical systems.

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Sonoluminescing bubbles and mass diffusion

Cited by 134 publications

References 28 publications

Single-bubble sonoluminescence

Single-bubble sonoluminescence

Phase diagrams for sonoluminescing bubbles

Mechanistic approach to enhancement of the yield of a sonochemical reaction

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