Dynamic drying transition via free-surface cusps

Catherine E M Kamal, james sprittles, Jacco Snoeijer, Jens Eggers*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

5 Citations (Scopus)
203 Downloads (Pure)


We study air entrainment by a solid plate plunging into a viscous liquid, theoretically and numerically. At dimensionless speeds Ca = Uη/γ of order unity, a near-cusp forms due to the presence of a moving contact line. The radius of curvature of the cusp’s tip scales with the slip length multiplied by an exponential of −Ca. The pressure from the air flow drawn inside the cusp leads to a bifurcation, at which air is entrained, i.e. there is ‘wetting failure’. We develop an analytical theory of the threshold to air entrainment, which predicts the critical capillary number to depend logarithmically on the viscosity ratio, with corrections coming from the slip in the gas phase.
Original languageEnglish
Pages (from-to)760-786
Number of pages27
JournalJournal of Fluid Mechanics
Early online date12 Nov 2018
Publication statusPublished - 10 Jan 2019


  • contact lines
  • gas/liquid flow
  • interfacial flows (free surface)

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