T. G. Leighton
Inst. of Sound & Vib. Res., Univ. of Southampton, Highfield, Southampton SO17 1BJ, England
There exists a range of acoustic techniques for characterizing bubble populations within liquids. Each technique has limitations, and complete characterization of a population requires the simultaneous use of several, so that the limitations of each find compensation in the others. An experiment is described in which a simple controlled bubble population is subjected to a driving signal at pump frequency, (omega)[inf p], and a second signal at the imaging frequency, (omega)[inf i]. The population is then simultaneous examined using geometrical scattering, and resonance scattering of the fundamental frequency ((omega)[inf p]), second and third harmonics (2(omega)[inf p], 3(omega)[inf p]), and combination frequencies ((omega)[inf i](plus or minus)(omega)[inf p] and (omega)[inf i](plus or minus)(omega)[inf p]/2). Comparison is made of the ease, accuracy, and speed with which individual techniques measure the population, and what advantages accrue from their simultaneous deployment.