Numerical analysis of the effect of bubble distribution on multiple-bubble behavior.

Area of Science:

• Fluid Dynamics
• Acoustics
• Nanotechnology

Background:

• Megasonic cleaning is crucial for nanodevice fabrication.
• Controlling multiple-bubble dynamics is key to preventing pattern damage during cleaning.

Purpose of the Study:

• To numerically investigate the effects of equilibrium radius and initial void fraction on multiple-bubble behavior.
• To analyze bubble collapse, coalescence, and breakup in a megasonic field.
• To understand induced pressure generation for optimized cleaning.

Main Methods:

• Utilized a compressible, locally homogeneous model for gas-liquid two-phase flow.
• Simulated bubbles with uniform equilibrium radius and with a bubble size distribution.
• Analyzed nonspherical bubble dynamics under megasonic irradiation.

Main Results:

• Bubble behavior and induced pressure are primarily dependent on the initial void fraction.
• For uniform bubble sizes, smaller bubbles create higher wall pressure at larger void fractions.
• Bubble size distribution leads to damping effects, reducing the contribution of small bubbles to wall pressure.

Conclusions:

• Initial void fraction is the dominant factor in megasonic multiple-bubble dynamics.
• Bubble size distribution can mitigate excessive pressure, preventing nanodevice damage.
• Large bubbles can suppress resonant bubble oscillations, further controlling pressure.