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dc.contributor.authorLangley, Kenneth
dc.contributor.authorLi, Erqiang
dc.contributor.authorThoroddsen, Sigurdur T
dc.date.accessioned2017-02-15T08:32:15Z
dc.date.available2017-02-15T08:32:15Z
dc.date.issued2017-01-23
dc.identifier.citationLangley K, Li EQ, Thoroddsen ST (2017) Impact of ultra-viscous drops: air-film gliding and extreme wetting. Journal of Fluid Mechanics 813: 647–666. Available: http://dx.doi.org/10.1017/jfm.2016.840.
dc.identifier.issn0022-1120
dc.identifier.issn1469-7645
dc.identifier.doi10.1017/jfm.2016.840
dc.identifier.urihttp://hdl.handle.net/10754/622896
dc.description.abstractA drop impacting on a solid surface must push away the intervening gas layer before making contact. This entails a large lubricating air pressure which can deform the bottom of the drop, thus entrapping a bubble under its centre. For a millimetric water drop, the viscous-dominated flow in the thin air layer counteracts the inertia of the drop liquid. For highly viscous drops the viscous stresses within the liquid also affect the interplay between the drop and the gas. Here the drop also forms a central dimple, but its outer edge is surrounded by an extended thin air film, without contacting the solid. This is in sharp contrast with impacts of lower-viscosity drops where a kink in the drop surface forms at the edge of the central disc and makes a circular contact with the solid. Larger drop viscosities make the central air dimple thinner. The thin outer air film subsequently ruptures at numerous random locations around the periphery, when it reaches below 150 nm thickness. This thickness we measure using high-speed two-colour interferometry. The wetted circular contacts expand rapidly, at orders of magnitude larger velocities than would be predicted by a capillary-viscous balance. The spreading velocity of the wetting spots is independent of the liquid viscosity. This may suggest enhanced slip of the contact line, assisted by rarefied-gas effects, or van der Waals forces in what we call extreme wetting. Myriads of micro-bubbles are captured between the local wetting spots.
dc.description.sponsorshipThe work reported herein was funded by King Abdullah University of Science and Technology (KAUST).
dc.publisherCambridge University Press (CUP)
dc.relation.urlhttps://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/div-classtitleimpact-of-ultra-viscous-drops-air-film-gliding-and-extreme-wettingdiv/798BDD556D6008324CB300EC56F80F16
dc.subjectContact lines
dc.subjectdrops and bubbles
dc.subjectthin films
dc.titleImpact of ultra-viscous drops: air-film gliding and extreme wetting
dc.typeArticle
dc.contributor.departmentClean Combustion Research Center
dc.contributor.departmentHigh-Speed Fluids Imaging Laboratory
dc.contributor.departmentMechanical Engineering Program
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.identifier.journalJournal of Fluid Mechanics
kaust.personLangley, Kenneth
kaust.personLi, Erqiang
kaust.personThoroddsen, Sigurdur T.
dc.date.published-online2017-01-23
dc.date.published-print2017-02


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