Single-bubble and multibubble cavitation in water triggered by laser-driven focusing shock waves

Area of Science:

• Fluid Dynamics
• Acoustics
• Laser Physics

Background:

• Cavitation, the formation and collapse of bubbles in a liquid, is a complex phenomenon driven by pressure changes.
• Understanding shock wave interactions with liquid interfaces is crucial for various applications, including material processing and medical treatments.

Purpose of the Study:

• To investigate the dynamics of shock-driven bubble cavitation induced by a ring-shaped laser pulse in a thin water layer.
• To analyze the nucleation and evolution of single and multiple cavitation bubbles and shock wave propagation.

Main Methods:

• Utilizing a single laser pulse spatially shaped into a ring and focused into a thin water layer.
• Employing time-resolved imaging to capture shock propagation and bubble wall motion.
• Performing numerical simulations using a one-dimensional Euler equation in cylindrical coordinates.

Main Results:

• Observed the creation of an annular cavitation bubble and cylindrical shock waves (diverging and converging).
• Documented the nucleation of a central bubble following the converging shock's divergence.
• Identified the reflection of the diverging inner shock at the annular bubble boundary, triggering tertiary bubble cloud nucleation.
• Experimental observations were consistent with numerical simulations, particularly for large bubble clouds at smaller laser ring sizes.

Conclusions:

• The technique of shock-driven bubble cavitation provides a novel method for studying cavitation phenomena.
• This approach offers new perspectives for investigating shock-induced single-bubble and multi-bubble cavitation in thin liquid layers.
• The findings contribute to a deeper understanding of fundamental cavitation physics and its potential applications.