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Author Basu, S.; Yawar, A.; Concha, A.; Bandi, M.M.
Title On angled bounce-off impact of a drop impinging on a flowing soap film Type
Year 2017 Publication Fluid Dynamics Research Abbreviated Journal Fluid Dyn. Res.
Volume 49 Issue 6 Pages 19 pp
Keywords drop impact; soap film; interfacial flow; bouncing drops
Abstract Small drops impinging obliquely on thin flowing soap films frequently demonstrate the rare emergence of bulk elastic effects working in-tandem with the more commonplace hydrodynamic interactions. Three collision regimes are observable: (a) drop piercing through the film, (b) it coalescing with the flow, and (c) it bouncing off the film surface. During impact, the drop deforms along with a bulk elastic deformation of the film. For impacts that are close-to-tangential, the bounce-off regime predominates. We outline a reduced order analytical framework assuming a deformable drop and a deformable three-dimensional film, and the idealization invokes a phase-based parametric study. Angular inclination of the film and the ratio of post and pre-impact drop sizes entail the phase parameters. We also perform experiments with vertically descending droplets (constituted from deionized water) impacting against an inclined soap film, flowing under constant pressure head. Model-predicted phase domain for bounce-off compares well to our experimental findings. Additionally, the experiments exhibit momentum transfer to the film in the form of shed vortex dipoles, along with propagation of free surface waves. On consulting prior published work, we note that for locomotion of water-walking insects using an impulsive action, the momentum distribution to the shed vortices and waves are both significant, taking up respectively 2/3 and 1/3 of the imparted streamwise momentum. Considering the visually similar impulse actions, this theory, despite its assumption of a quiescent liquid bath of infinite depth, is applied to the drop bounce-off experiments, and the resultant shed vortex dipole momenta are compared to the momenta of the coherent vortex structures computed from particle imaging velocimetry data. The magnitudes reveal identical order (10(-7) N s), suggesting that notwithstanding the disparities, the bounce-off regime may be tapped as a toy analog for impulse-based interfacial biolocomotion.
Address [Basu, Saikat; Yawar, Ali; Bandi, M. M.] Okinawa Inst Sci & Technol, Grad Univ, Collect Interact Unit, Onna Son, Okinawa 9040495, Japan, Email: saikat_basu@med.unc.edu
Corporate Author Thesis
Publisher Iop Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue (up) Edition
ISSN 0169-5983 ISBN Medium
Area Expedition Conference
Notes WOS:000415620000002 Approved
Call Number UAI @ eduardo.moreno @ Serial 789
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