Further study of the effects of shear viscosity on inertial cavitation thresholds

Abstract

Initial research [Allen etal., J. Acoust. Soc. Am. 96, 3306(A) (1994)] on accessing the effects of shear viscosity on inertial cavitation thresholds has been extended in order to further explicate previous results. Thresholds for inertial cavitation in water and biological media modeled as a viscous fluid were calculated using a numerical implementation of the Gilmore equation for adiabatic bubble oscillations [Church, J. Acoust. Soc. Am. 83, 2210–2217 (1988)]. The threshold criterion was chosen to be a bubble collapse temperature of 5000 K as to facilitate comparison with the analytical theory of Holland and Apfel [IEEE-UFFC 36, 204 (1989)]. The scaling of the calculated pressure thresholds with initial bubble radius was previously not sufficiently explained by linear resonance theory. The addition of calculations of the ‘‘nonlinear resonance’’ sizes, however, more adequately explains this scaling. Furthermore, the nonlinear resonance size is shown to be a more accurate indicator of the bubble sizes most likely to undergo inertial cavitation than the linear resonance size. The qualitative physics pertaining to these additional results is highlighted along with comparisons to recent experimental measurements [Zheng etal., J. Acoust. Soc. Am. 95, 2855(A) (1994)]. [Work supported by NIH through Grant No. RO1 CA39374.]