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Annu. Rev. Fluid Mech. 2000. 32:445–476
Copyright ᭧ 2000 by Annual Reviews. All rights reserved

SONOLUMINESCENCE: How Bubbles Turn Sound into Light
S. J. Putterman and K. R. Weninger
Physics Department, University of California, Los Angeles, California 90095; e-mail: putterman@physics.ucla.edu Annu. Rev. Fluid Mech. 2000.32:445-476. Downloaded from arjournals.annualreviews.org by NORTH CAROLINA STATE UNIVERSITY on 08/14/09. For personal use only.

Key Words energy focusing, nonlinear dynamics, complexity, hydrodynamics gas bubble, continuum mechanics, shock shape instabilities, chemical hydrodynamics
Abstract Sonoluminescence, the transduction of sound into light, is a phenomenon that pushes fluid mechanics beyond its limit. An initial
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In particular an imposed sound wave with a Mach number that is small compared with unity and a wavelength that is large compared with the mean free path can, in the presence of a bubble, focus its energy in a runaway fashion so as to generate picosecond flashes of broad-band UV light (Barber & Putterman 1991, Hiller et al 1992,
Hiller et al 1994, Barber et al 1997a, Putterman 1998, Crum 1994, Putterman
1995). The energy of a UV photon compared with that of a single atom vibrating
0066–4189/00/0115–0445$12.00

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PUTTERMAN Ⅲ WENINGER

Annu. Rev. Fluid Mech. 2000.32:445-476. Downloaded from arjournals.annualreviews.org by NORTH CAROLINA STATE UNIVERSITY on 08/14/09. For personal use only.

in the imposed sound field represents an energy focusing that spans 12 orders of magnitude. Nature’s tendency to focus energy in the off-equilibrium motion of fluids is spectacularly robust. Figure 1 shows a photo of a single bubble attached to a wire in an acoustically excited fluid (Weninger et al 1997). Owing to the boundary conditions imposed by the wire, the bubble is not spherical but is distorted into an approximation of a hemisphere. Yet this bubble pulsates synchronously with the sound field, expanding during the rarefaction part of the acoustic cycle and collapsing so strongly during the ensuing compression that the input acoustic energy is transduced into UV

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