Bubble oscillations

Abstract Sonoluminescence from alkali-metal salt solutions reveals excited state alkali - metal atom emission which exhibits asymmetrically-broadened lines. The location of the emission site is of interest as well as how nonvolatile ions are reduced and electronically excited. This chapter reviews sonoluminescence studies on alkali-metal atom emission in various environments. We focus on the emission mechanism does the emission occur in the gas phase within bubbles or in heated fluid at the bubble/liquid interface Many studies support the gas phase origin. The transfer of nonvolatile ions into bubbles is suggested to occur by means of liquid droplets, which are injected into bubbles during nonspherical bubble oscillation, bubble coalescence and/or bubble fragmentation. The line width of the alkali-metal atom emission may provide the relative density of gas at bubble collapse under the assumption of the gas phase origin. 

In general for small P /Ph ratios, with (the resonant bubble radius), oscillations take place at approximately the excitation frequency (Fig. 2.21). For R > Rj, bubble oscillation has a strong component of its ovm natural resonant frequency (Fig. 2.22). However for very small bubbles, R. << R, transient conditions are attained as P increases beyond Pjj (Fig. 2.23, P = 4 and 10 atm). It may be that as... 

Number of Bubble Oscillations Before Bubble Reaches Surface (for a TNT Bubble). U 54... 

Reduced Charge Depthd/w"3 (m/kg1/3) Number of Bubble Oscillations Before Reaching Surface... 

Nsur rate of energy dissipation due to bubble oscillation per unit mass, m2/ s3... 

Statistical methods based on measuring energy or radial velocity in the liquid in the cavitation field thermal methods, acoustic output, and measurement of velocity associated with bubble oscillation. 

A rough estimate for the normal fluid results in Tb = 4 x 10 s [99]. The bubble oscillation time xq in the well of the image potential can be inferred from Eq. (87), with the third term on the left-hand side of this equation being neglected, resulting in... 

E is the initial potential energy in the image potential, v(r) is the velocity of the bubble motion with its center at distance r from the cluster center, Y is the period of the bubble oscillation, and Fim(t) is the image potential, [Eq. (88)]. In this case the electron current I t) was calculated in the form... 

Bashforth F and Adams JC (1883) An attempt to test the capillary action, Cambridge University Press and Deighton Bell Co., Cambridge Chen P, Kwork DY, Prokop RM, del-Rio 01, Susnar SS and Neumann AW (1998) Axisymmetric drop shape analysis (ADSA) and its applications , in Drops and bubbles in interfacial research, D. Moebius and R. Miller Eds., Studies in Interface Science Series, Vol. 6, Elsevier, Amsterdam Dukhin SS, Kretzschmar G and R. Miller R (1995) Dynamic of adsorption at liquid interfaces. Theory, experiments, applications, D. Moebius and R. Miller Eds., Studies in Interface Science Series, Vol. 1, Elsevier, Amsterdam Joos P (1999) Dynamic Surface Phenomena, VSP, Utrecht, 1999 Kovalchuk VI, Zholkovskij EK, Kragel J, Miller R, Fainerman VB, Wiistneck R, Loglio G and Dukhin SS (2000) Bubble Oscillations in a Closed Cell. J Colloid Interface Sci 224 245-254... 

Bubble Oscillations Due to Periodic Pressure Oscillations - Resonance and Multiple-Time-Scale-Analysis... 

Note, however, that once G is negative, the effect of increased k, in a system with no viscous damping, is to produce bubble oscillation at higher frequency. 

J.P. Raven and P. Marmottant, Periodic microfluidic bubbling oscillator Insight into the stability of two-phase microflows, Physical Review Letters, 97, (2006). 

The principle of the experiment is shown in Fig. 6.5. A small air bubble is formed at the tip of a capillary which is immersed in the solution. Via an electrodynamic excitation system and a membrane, a gas volume directly connected with the capillary is excited to harmonic oscillations. From the excitation voltage of the system in dependence on frequency, while keeping the bubble oscillation amplitude constant, the dilational elasticity and the exchange of matter can be calculated. The comparatively complex theory for data interpretation was described recently by Wantke et al. (1980, 1993). The method can be applied in a frequency interval from 5 Hz up to about 150 Hz. 

A comprehensive analysis of oscillating drops and bubbles has been performed recently [207, 208, 209]. The apparatus shown schematically in Fig. 4.17 is designed according to the conditions analysed there. It has been shown that this type of geometries and measuring cells fulfils the requirements for stable radial drop or bubble oscillations best. 

As one can see the experimental set-up allows to register the initial stage of the bubble oscillation. Here a transient regime of non-established harmonic oscillations is clearly observed for larger frequencies and the measured pressure oscillation is a sum of a non-damped oscillation of the externally applied frequency and a damped oscillation with the meniscus eigenfrequency (for details cf. [208]). At larger frequencies the damped oscillation contribution as shown in Fig. 4.46c is practically absent as the damping time is sufficiently small. 

Liquids irradiated with ultrasound can produce bubbles. These bubbles oscillate and grow a little more during the expansion phase of the sound wave than they shrink during the compression phase. Under the proper conditions these bubbles can undergo cavitation, violent bubble collapse or implosion, leading to droplets particle size reduction. The use of ultrasonication in emulsification is more efficient than rotor-stator systems. 

Lauterbom W, Kurz T (2010) Physics of bubble oscillations. Rep Prog Phys 73 106501... 

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