Laser-Induced Single Cavitation Bubble Dynamics in the Presence of Microscale Roughness

Area of Science:

• Fluid Dynamics
• Materials Science
• Surface Engineering

Background:

• Cavitation-induced erosion is a significant issue in hydraulic and marine systems.
• Bubble collapse near solid boundaries generates damaging forces.

Purpose of the Study:

• To investigate the efficacy of microstructured rough surfaces as a passive control technique against cavitation erosion.
• To analyze the influence of surface micro-roughness on bubble collapse dynamics.

Main Methods:

• High-speed imaging was used to observe single bubble collapse dynamics.
• Laser-generated plasma induced bubble formation near smooth and microscale rough surfaces.
• Bubble radius evolution was tracked at varying relative wall distances.

Main Results:

• Smooth surfaces induced symmetrical bubble collapse, forming toroidal structures attached to the wall.
• Microscale rough surfaces induced asymmetric collapse and rebound, generating a counter-jet moving away from the surface.
• Roughness diminished microjet momentum and toroidal cavity size, reducing erosion potential.

Conclusions:

• Microscale surface roughness significantly alters bubble dynamics during collapse.
• This alteration effectively mitigates the damaging effects of cavitation, offering a novel erosion control strategy.
• Surface modification presents a promising passive approach for reducing cavitation erosion in critical systems.