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Optic generation and perpetuation of acoustic bubble clusters
Jaka Mur1, Fabian Reuter2, Vid Agrež3
1Faculty of Natural Sciences, Institute for Physics, Otto-von-Guericke-University Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany; Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, SI-1000 Ljubljana, Slovenia.
Ultrasonics Sonochemistry
|August 17, 2024
Summary
This study introduces a novel method combining laser-induced cavitation bubbles with ultrasound for controlled liquid processing. This hybrid approach enables precise manipulation of bubble dynamics, overcoming limitations of traditional acoustic cavitation.
Area of Science:
- Fluid Dynamics
- Acoustics
- Laser Physics
Background:
- Conventional acoustic cavitation offers limited control over bubble dynamics and energy deposition in liquid processing.
- Laser-induced cavitation provides precise spatial and temporal control but is underutilized in liquid processing.
Purpose of the Study:
- To develop and investigate a hybrid method for controlled cavitation bubble generation and manipulation.
- To explore the potential of combining laser nucleation with ultrasound driving for enhanced liquid processing.
Main Methods:
- A custom pulsed laser was used to nucleate single cavitation bubbles below a 20 kHz sonotrode.
- The dynamics of laser-induced cavitation bubbles were studied under ultrasound driving, both in free field and near a rigid boundary.
- Bubble splitting and cluster formation were analyzed, along with the effect of repetitive optical seeding.
Main Results:
- A single laser-induced bubble, in the absence of ultrasound, reached 130 µm diameter with a 10 µs lifetime.
- Ultrasound driving caused bubble splitting and cluster formation, with dynamics influenced by nucleation phase.
- Repetitive optical seeding allowed control over bubble cluster lifetime and location, even after initial connection to nucleation phase was lost.
Conclusions:
- The hybrid laser-ultrasound method offers superior cavitation control compared to conventional acoustic methods.
- This technique allows for targeted energy delivery and manipulation of bubble dynamics for potential applications in mechanical and chemical processing.
- Controlled bubble cluster formation and longevity were achieved through precise laser initiation and acoustic manipulation.
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