Shock-induced collapse of surface nanobubbles

Area of Science:

• Fluid dynamics
• Materials science
• Nanotechnology

Background:

• Cavitation bubble collapse generates high-speed jets causing surface damage.
• Surface nanobubbles are known cavitation nucleation sites but their collapse dynamics are unstudied.
• Applications include drug delivery, cancer treatment, and surface cleaning.

Purpose of the Study:

• Investigate the collapse dynamics of surface nanobubbles.
• Compare jet formation and substrate damage with spherical nanobubbles.
• Explore the influence of nanobubble size and contact angle on damage.

Main Methods:

• Molecular dynamics simulations of shock-induced collapse.
• Modeling of surface nanobubbles with varying sizes and contact angles.
• Comparison with simulations of collapsing spherical nanobubbles near a substrate.

Main Results:

• Surface nanobubble collapse causes significantly reduced pitting damage compared to spherical nanobubbles.
• Weaker jet formation is the primary reason for reduced damage from surface nanobubbles.
• Surface nanobubble pit depth depends on contact angle, not bubble size, unlike spherical bubbles.
• A linear scaling relationship was found between substrate damage and peak pressure impulse.

Conclusions:

• Surface nanobubbles offer controlled surface modification due to weaker cavitation jets.
• The findings enable better assessment of bubble collapse damage in computational studies.
• Potential for new applications in advanced manufacturing, medicine, and precision cleaning.