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Free-surface flows under impacting droplets

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Title: Free-surface flows under impacting droplets
Authors: Watanabe, Yasunori Browse this author →KAKEN DB
Saruwatari, Ayunii Browse this author
Ingram, David M. Browse this author
Keywords: droplet impact
vortex ring
free-surface boundary condition
level-set method
Issue Date: 1-Feb-2008
Publisher: Academic Press
Journal Title: Journal of Computational Physics
Volume: 227
Issue: 4
Start Page: 2344
End Page: 2365
Publisher DOI: 10.1016/
Abstract: A numerical method which fulfils the free-surface boundary conditions and extrapolates the fluid velocity in to empty grid cells outside the fluid region on a fixed Cartesian grid system is presented. The complex, three-dimensional, vortex structures formed via surface/vortex interaction and induction between vortices have been computed using the proposed technique implemented within a level-set method for both vertical and oblique droplet impacts in incompressible fluids. The present results have been validated through numerical tests which confirm zero tangential shear at the free-surface and comparisons with experimental observations of cavity and vortex ring formation underneath the impact location. In some cases, transitions from a concentric vortex ring to a fully three-dimensional vortex structure has been confirmed. Whilst the primary vortex ring is initiated at the highly curved contact surface between the droplet and receiving surface, azimuthal instabilities are manifested in the shear layer around the cavity crater developing after the vertical impact, resulting in axial counter-rotating vorticity between the cavity and descending vortex ring. Underlying mechanisms which induce local deformation of the free-surface, creating a so-called scar, due to the sub-surface vortices at the oblique impacts are also discussed.
Type: article (author version)
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 渡部 靖憲

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