Acoustic waves for active reduction of contact time in droplet impact

Research output: Contribution to journalArticlepeer-review


  • Mehdi H. Biroun
  • Jie Li
  • Ran Tao
  • Mohammad Rahmati
  • Glen McHale
  • Linxi Dong
  • Hamdi Torun
  • Yong Qing Fu

Colleges, School and Institutes

External organisations

  • Northumbria University Newcastle
  • Hangzhou Dianzi University
  • College of Computer Science and Software Engineering, Shenzhen University, Shenzhen, China.
  • Department of Mechanical Engineering


Minimizing droplet impact contact time is critical for applications such as self-cleaning, antierosion or anti-icing. Recent studies have used the texturing of surfaces to split droplets during impact or inducing asymmetric spreading, but these require specifically designed substrates that cannot be easily reconfigured. A key challenge is to realize an effective reduction in contact time during droplet impingement on a smooth surface without texturing but with active and programmable control. Our experimental results show that surface acoustic waves (SAWs), generated at a location distant from a point of droplet impact, can be used to minimize contact time by as much as 35% without requiring a textured surface. Additionally, the ability to switch on and off the SAWs means that a reduction in droplet impact contact time on a surface can be controlled in a programmable manner. Moreover, our results show that, by applying acoustic waves, the impact regime of the droplet on the solid surface can be changed from deposition or partial rebound to complete rebound. To study the dynamics of droplet impact, we develop a numerical model for multiphase flow and simulate different droplet impingement scenarios. Numerical results reveal that the acoustic waves can be used to modify and control the internal velocity fields inside the droplet. By breaking the symmetry of the internal recirculation patterns inside the droplet, the kinetic energy recovered from interfacial energy during the retraction process is increased, and the droplet can be fully separated from the surface with a much shorter contact time. Our work opens up opportunities to use SAW devices to minimize the contact time, change the droplet impact regime, and program or control the droplet's rebounding on smooth or planar and curved surfaces, as well as rough or textured surfaces.

Bibliographic note

Funding Information: This work is financially supported by the UK Engineering and Physical Sciences Research Council (EPSRC) Grant No. EP/P018998/1 and the Special Interests Group of Acoustofluidics under the EPSRC-funded UK Fluidic Network (Grant. No. EP/N032861/1). Publisher Copyright: © 2020 American Physical Society. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.


Original languageEnglish
Article number024029
JournalPhysical Review Applied
Issue number2
Publication statusPublished - Aug 2020

ASJC Scopus subject areas