Ultrasonic Atomization Techniques in Fluid Dynamics

Ultrasonic atomisation harnesses high-frequency mechanical vibrations to transform bulk liquids into fine sprays, exploiting capillary wave amplification and cavitation phenomena at the liquid–air interface. A piezoelectric transducer or vibrating mesh induces standing surface waves whose amplitudes grow until droplets detach when hydrodynamic instabilities overcome surface tension. Key parameters influencing droplet formation include vibration frequency, amplitude, liquid viscosity and surface tension, and the geometry of apertures or sonotrodes. Ultrasonic methods yield narrow droplet size distributions, reduced mechanical stress and enhanced control over particle morphology, making them invaluable in applications ranging from pulmonary drug delivery and spray cooling to fuel injection and powder production for additive manufacturing. Recent advances have elucidated the interplay between Faraday instabilities, ligament corrugation and inertial cavitation during atomisation, while novel transducer designs and in situ imaging techniques have deepened our understanding of atomisation dynamics. Global interest has surged in optimising energy efficiency, tailoring droplet characteristics for multifunctional coatings and expanding micrometre-scale atomisation to emerging sectors such as precision agriculture and microencapsulation.

Research from Nature Portfolio

Recent studies have systematically characterised droplet size distributions produced by ultrasonic nebulisers, revealing that the breakup mechanism is governed by the pinch-off of capillary ligaments formed through Faraday wave instabilities. Analysis shows that droplet size distributions align with those found in conventional sprays, where the wavelength of standing capillary waves and surface corrugation dictate ligament formation. Investigators have demonstrated that the median droplet diameter scales directly with the capillary wavelength, with only minor dependence on device design, thereby providing a predictive framework for tailoring droplet sizes across different nebuliser technologies.

Ultrasonic Atomization Techniques in Fluid Dynamics publication trend

The graph below shows the total number of articles in ultrasonic atomization techniques in fluid dynamics across all publications each year (not limited to Nature Index journals).

Technical terms

Ultrasonic atomisation: Production of liquid droplets via high-frequency vibrations that generate capillary waves and instabilities.

Capillary waves: Surface waves driven by an external force whose restoring mechanism is surface tension.

Faraday instability: Formation of standing wave patterns on a fluid surface under periodic vertical or horizontal forcing.

Cavitation: Rapid formation and collapse of vapour bubbles in a liquid subjected to local pressure variations.

Piezoelectric transducer: A device that converts electrical signals into mechanical vibrations using piezoelectric materials.

Droplet size distribution: Statistical description of the range and frequency of droplet diameters in a spray.

References

1. Size distributions of droplets produced by ultrasonic nebulizers. Scientific Reports (2019).
2. New insights into the mechanism of ultrasonic atomization for the production of metal powders in additive manufacturing. Additive Manufacturing (2024).
3. Development of High-Power Ultrasonic System Dedicated to Metal Powder Atomization. Applied Sciences (2023).
4. Ultrasonic Atomization: New Spray Characterization Approaches. Fluids (2022).