Microbubble shape oscillations excited through ultrasonic parametric driving.
An air bubble driven by ultrasound can become shape-unstable through a parametric instability. We report time-resolved optical observations of shape oscillations (mode n=2 to 6) of micron-sized single air bubbles. The observed mode number n was found to be linearly related to the ambient radius of the bubble. Above the critical driving pressure threshold for shape oscillations, which is minimal at the resonance of the volumetric radial mode, the observed mode number n is independent of the forcing pressure amplitude. The microbubble shape oscillations were also analyzed numerically by introducing a small nonspherical linear perturbation to a Rayleigh-Plesset-type equation, capturing the experimental observations in detail.
Versluis
Michel
M
Department of Science and Technology, University of Twente, 7500 AE Enschede, The Netherlands.
Goertz
David E
DE
Palanchon
Peggy
P
Heitman
Ivo L
IL
van der Meer
Sander M
SM
Dollet
Benjamin
B
de Jong
Nico
N
Lohse
Detlef
D