Miscibility and wettability: how interfacial tension influences droplet impact onto thin wall films

Ronan Bernard, David Baumgartner, Günter Brenn, Carole Planchette, Bernhard Weigand, Grazia Lamanna

Research output: Contribution to journalArticle

Abstract

The influence of miscibility and liquid wettability during droplet impact onto thin wall films is investigated experimentally. Despite similar liquid properties and impact conditions, differences in the splashing limit, in the crown extension and in the duration of the ascending phase are observed. These differences are related to the interfacial tension of the droplet/wall-film liquid pairs, which is linked to their miscibility and wettability. More precisely, by calculating the crown surface energy, we show that the energy stored in the interface between droplet and wall film (if any) is not negligible and leads to smaller crown extensions and tendentially the need for more kinetic energy to initiate splashing. Similarly, by calculating a modified capillary time taking into account all surface and interfacial tensions, we show that the interfacial tension acts as a non-negligible recoiling force, which reduces the duration of the ascending phase. The dynamics of this ascending phase is well captured for different wall-film thicknesses if accounting for the variations of the liquid masses in movement. Overall, droplet/wall-film interactions can be seen as inertio-capillary systems where the interfacial tension between droplet and wall film plays a significant role in the storage of energy and in the crown kinetics during the impact process. In addition, this analysis highlights that viscous losses have already a significant effect during the crown extension phase, by dissipating almost half of the initial energies for droplet impact onto thin wall films, and most likely by influencing the capillary time scale through damping.

Original languageEnglish
Article numberA36
Number of pages24
JournalJournal of Fluid Mechanics
Volume908
Early online date1 Jan 2020
DOIs
Publication statusPublished - 2021

Keywords

  • breakup/coalescence
  • drops
  • thin films

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Fields of Expertise

  • Advanced Materials Science
  • Human- & Biotechnology

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