Acoustic Sensing of Forces Driving Fast Capillary Flows

Area of Science:

• Fluid dynamics
• Aeroacoustics
• Acoustics

Background:

• The sound produced by bursting soap bubbles is a common phenomenon.
• Understanding the physics behind such sounds can offer insights into fluid dynamics and material stresses.

Purpose of the Study:

• To analyze the acoustic emission from bursting soap bubbles.
• To demonstrate that the sound quantitatively reflects the liquid film's evolution and the forces involved.

Main Methods:

• Acquisition of bubble bursting sound using microphone arrays.
• Analysis of acoustic data via spherical harmonics decomposition.
• Application of aeroacoustics theoretical framework.

Main Results:

• The acoustic emission primarily originates from capillary stresses exerted by the soap film on the air.
• The sound quantitatively reflects the out-of-equilibrium evolution of the liquid film.
• Proof of concept for using acoustic signatures to measure forces in violent events.

Conclusions:

• The sound of a bursting soap bubble is a direct indicator of the forces within the liquid film.
• Acoustic signatures can be utilized to measure forces during rapid physical or biological events.
• This study opens avenues for non-invasive force measurement in dynamic processes.