The use of molecular and continuum emission spectra from multiple bubble (MB) and single bubble (SB) sonoluminescence (SL) is explored as a probe of bubble temperature during cavitational collapse. It is proposed that molecular and continuum SL arise from different chemical pathways, which occur during discrete intervals along the cavitational collapse time line, thus yielding different cavitat...

Cavitation greatly affects the safe and stable operation of hydraulic machineries thus has been key challenge in this field. Cavity collapse caused by cavitation can form transient characteristics such as high temperature, pressure, strong shock wave, high-speed micro-jet, which may cause serious damage to nearby solids. be affected many intercoupled factors during transition. However, existing...

Ultrasound contrast agents (UCAs) are micron-sized gas bubbles encapsulated with thin shells on the order of nanometers thick. The damping effects of these viscoelastic coatings are widely known to significantly alter the bubble dynamics for linear and low-amplitude behavior; however, their effects on strongly nonlinear and destruction responses are much less studied. This dissertation examines...

Surface cleaning using cavitation bubble dynamics is investigated numerically through modeling of bubble dynamics, dirt particle motion, and fluid material interaction. Three fluid dynamics models; a potential flow model, a viscous model, and a compressible model, are used to describe the flow field generated by the bubble all showing the strong effects bubble explosive growth and collapse have...

Cavitation in solid-water mixtures generated by ultrasonic waves can be used to modify the topography of metallic surfaces. During ultrasonic irradiation two kinds of processes occur in the liquid: (a) material removal by bubble formation plus collapse and the resulting micro jets; (b) material removal by colliding or sliding of accelerated particles due to bubble formation plus collapse. Both ...

A strong laser pulse that is focused into a liquid produces a vapor cavity, which first expands and then collapses with subsequent rebounds. In this paper a mathematical model of the spherically symmetric motion of a laser-induced bubble is proposed. It describes gas and liquid dynamics including compressibility, heat, and mass transfer effects and nonequilibrium processes of evaporation and co...

Submit Manuscript | http://medcraveonline.com 100 kHz) can provide the mechanical effect of cavitation in liquid systems which can alter physical and chemical properties of food depending on the type of material involved. When ultrasound waves pass through a medium, a series of compression and rarefaction waves on the molecules of the medium are produced. This enforces a sinusoidal acoustic pre...

Pairs of unequal strength, counter-rotating vortices were produced in order to examine the inception, dynamics, and acoustic emission of cavitation bubbles in rapidly stretching vortices. The acoustic signatures of these cavitation bubbles were characterized during their inception, growth, and collapse. Growing and collapsing bubbles often produced a sharp, broadband, pop sound. The spectrum of...

Spherically collapsing cavitation bubbles produce a shock wave followed by a rebound bubble. Here we present a systematic investigation of the energy partition between the rebound and the shock. Highly spherical cavitation bubbles are produced in microgravity, which suppresses the buoyant pressure gradient that otherwise deteriorates the sphericity of the bubbles. We measure the radius of the r...

An ultrasound technique to measure the spatial and temporal behavior of the laser-induced cavitation bubble is introduced. The cavitation bubbles were formed in water and in gels using a nanosecond pulsed Nd:YAG laser operating at 532 nm. A focused, single-element, 25-MHz ultrasound transducer was employed both to detect the acoustic emission generated by plasma expansion and to acoustically pr...