Acoustic cavitation and bubble dynamics.

The topic of this chapter, acoustic cavitation, is but one of several possible mechanisms through which ultrasound can interact with a liquid medium. Acoustic cavitation can affect a liquid through two possible avenues. The liquid is disrupted by the inhomogeneous presence of the bubble. The second avenue through which bubbles affect a fluid is through bubble dynamics. The bubble's interior and the liquid immediately surrounding the bubble are regions which undergo continual change. The bubble liquid interface continually changes shape and size; liquid molecules diffuse into and out of the bubble; the concentration of gas in the surrounding liquid varies; acoustic streaming occurs in the liquid in the vicinity of the bubble often resulting in severe shear stresses; the interior pressure and temperature fluctuate rapidly; the bubble radiates acoustic energy as it oscillates; thermal and viscous damping hinder the bubble oscillations.