Type
ArticleKAUST Department
Clean Combustion Research CenterHigh-Speed Fluids Imaging Laboratory
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
Date
2013-04-29Online Publication Date
2013-04-29Print Publication Date
2013-06Permanent link to this record
http://hdl.handle.net/10754/334508
Metadata
Show full item recordAbstract
We use ultra-high-speed video imaging to look at the initial contact of a drop impacting on a liquid layer. We observe experimentally the vortex street and the bubble-ring entrapments predicted numerically, for high impact velocities, by Thoraval et al. (Phys. Rev. Lett., vol. 108, 2012, article 264506). These dynamics mainly occur within 50 -s after the first contact, requiring imaging at 1 million f.p.s. For a water drop impacting on a thin layer of water, the entrapment of isolated bubbles starts through azimuthal instability, which forms at low impact velocities, in the neck connecting the drop and pool. For Reynolds number Re above -12 000, up to 10 partial bubble rings have been observed at the base of the ejecta, starting when the contact is -20% of the drop size. More regular bubble rings are observed for a pool of ethanol or methanol. The video imaging shows rotation around some of these air cylinders, which can temporarily delay their breakup into micro-bubbles. The different refractive index in the pool liquid reveals the destabilization of the vortices and the formation of streamwise vortices and intricate vortex tangles. Fine-scale axisymmetry is thereby destroyed. We show also that the shape of the drop has a strong influence on these dynamics. 2013 Cambridge University Press.Citation
Thoraval M-J, Takehara K, Etoh TG, Thoroddsen ST (2013) Drop impact entrapment of bubble rings. J Fluid Mech 724: 234-258. doi:10.1017/jfm.2013.147.Publisher
Cambridge University Press (CUP)Journal
Journal of Fluid MechanicsarXiv
1211.3076ae974a485f413a2113503eed53cd6c53
10.1017/jfm.2013.147
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