Acoustic microbubble dynamics with viscous effects

This paper examines acoustic microbubble dynamics with viscous effects, important for biomedical ultrasonics, sonochemistry, and cavitation cleaning.

The research presents a computational approach using boundary integral method based on viscous potential flow theory. The model incorporates viscous effects through normal viscous stress of irrotational flow at the bubble surface, with a viscous correction pressure to address shear stress discrepancies.

The model demonstrates excellent agreement with the Rayleigh-Plesset equation for spherical bubble oscillation in viscous liquid (Reynolds number Re = 10) and correlates well with experimental data and Navier-Stokes simulations for bubble dynamics near rigid boundaries. Analysis of microbubbles near rigid boundaries under ultrasound reveals that bubbles concentrate energy from ultrasound waves, resulting in violent collapse and jetting with velocities around 100 m/s. Near rigid boundaries, jet velocity decreases but cross-sectional area increases. Jet direction varies based on ultrasound direction and bubble distance from the boundary, while viscous effects primarily reduce oscillation amplitude and period rather than significantly altering jet direction.

The research provides valuable insights for medical applications including extracorporeal shock wave lithotripsy, tissue ablation (histotripsy), and ultrasonic cleaning of medical devices, advancing understanding of microbubble behavior in clinically relevant parameter ranges.