Shock wave emission upon spherical bubble collapse during cavitation-induced megasonic surface cleaning

Area of Science:

• Fluid dynamics
• Acoustics
• Materials science

Background:

• Acoustic waves interacting with bubbles near surfaces cause bubble expansion and collapse.
• Bubble collapse generates shock waves with significant energy.

Purpose of the Study:

• To develop a mathematical framework for modeling shock waves from bubble collapse.
• To analyze factors influencing shock wave strength and potential impact on microelectronics.

Main Methods:

• Combined the Gilmore model with the method of characteristics.
• Performed numerical calculations of liquid velocity at the shock front.
• Investigated effects of acoustic amplitude, initial bubble radius, gas state equations, and surface tension.

Main Results:

• Liquid velocity at the shock front increases with acoustic amplitude.
• Velocity exhibits a maximum as a function of initial bubble radius.
• Van der Waals law predicts higher velocity than the perfect gas law.
• Decreased surface tension increases shock wave velocity.

Conclusions:

• The mathematical framework accurately models shock wave emission during bubble collapse.
• Shock wave strength is influenced by acoustic amplitude, bubble size, gas properties, and surface tension.
• Emitted shock waves can cause delamination in microelectronic device structures.