The dynamics of the aspheric encapsulated bubble

Area of Science:

• Fluid dynamics
• Acoustics
• Materials science

Background:

• Spherical acoustic drives typically induce spherical bubble oscillations.
• Cavitation bubbles are known to be unstable under such conditions.
• Encapsulated bubbles offer unique possibilities for controlled oscillations.

Purpose of the Study:

• To develop a model for aspheric encapsulated bubbles (AEBs) driven by spherical ultrasound.
• To investigate the stability and oscillation characteristics of AEBs.
• To analyze the influence of initial shape and shell thickness on AEB behavior.

Main Methods:

• Hydrodynamic and elastic mechanics modeling.
• Numerical simulations of ovoid encapsulated bubbles.
• Analysis of bubble surface asphericity and shell thickness distribution.

Main Results:

• AEBs demonstrate stable aspheric oscillations under spherical acoustic drive, a behavior not observed in cavitation bubbles.
• Initial aspheric shape and shell thickness distribution are critical factors affecting AEB oscillation amplitude.
• Thinner shells lead to larger pulsation amplitudes due to reduced stiffness.

Conclusions:

• The developed model accurately predicts AEB behavior under acoustic forcing.
• AEB asphericity degrades the bubble's resistance to rupture.
• AEB asphericity reduces the maximum tolerable driving pressure before rupture.