The Non-Linear Oscillations of Multiple Bubbles in a Simulated Acoustic Field

Gas bubbles in liquids are capable of forced oscillations in a sound eld.Photographic study of these non-linear oscillations is difficult.It is technically most feasible at low acoustic frequencies.where lower framing rates are required.and where the resonance bubble size is larger.However. the acoustic pressures required to elicit a nonlinear response from the bubble might.if generated at audible frequencies.be damaging to the hearing.This paper outlines an experimental solution to the problem.whereby a volume of liquid containing bubbles of a size which can be readily photographed.is vibrated vertically.The oscillating pressure in the water mimics an acoustic eld at the vibration frequency, and the bubble responds to it as such.The apparatus has minimal audible emissions.yet-the oscillating pressure is of such an amplitudeas to generate highly nonlinearoscillations in the bubble.The experiment provides a good example of forced oscillation, as well as illustrating a subtle solution to a dif cult experimental problem.Radius-time data from a given bubble were obtained using high-speed and stroboseopic photography.and were compared with the numerical predictions obtained from the Rayleigh-Picsset equation.