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On the mechanics of droplet surface crater during impact on immiscible viscous liquid pool

Roy, D and Sophia, M and Basu, S (2023) On the mechanics of droplet surface crater during impact on immiscible viscous liquid pool. In: Journal of Fluid Mechanics, 955 .

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Official URL: https://doi.org/10.1017/jfm.2022.1071


We study drop impacts on an immiscible viscous liquid pool and investigate the formation of droplet surface craters using experimental and theoretical analyses. We attribute the formation of air craters to the rapid deceleration of the droplet due to viscous drag force. The droplet response to the external impulsive decelerating force induces oscillatory modes on the surface exposed to the air forming capillary waves that superimpose to form air craters of various shapes and sizes. We introduce a non-dimensional parameter , that is, the ratio of the drag force to the capillary force acting on the droplet. We show that is directly proportional to the capillary number. We show that droplets forming air craters of significant depths have 1]]>. Further, we demonstrate that Legendre polynomials can locally approximate the central air crater jet profile. We also decipher that the air crater response time scale varies as the square root of impact Weber number . Further, we generalize the local droplet response with a global response model for low impact energies based on an eigenvalue problem. We represent the penetrating drop as a constrained Rayleigh drop problem with a dynamic contact line. The air-water interface dynamics is analysed using an inviscid droplet deformation model for small deformation amplitudes. The local and global droplet response theories conform with each other and depict that the deformation profiles could be represented as a linear superposition of eigenmodes in Legendre polynomial basis. We unearth that the droplet response in an immiscible impact system differs from the miscible impact systems due to the presence of such a dynamic contact line. © The Author(s), 2023. Published by Cambridge University Press.

Item Type: Journal Article
Publication: Journal of Fluid Mechanics
Publisher: Cambridge University Press
Additional Information: The copyright for this article belongs to the Authors.
Keywords: Drag; Drop breakup; Eigenvalues and eigenfunctions; Phase interfaces, Contact lines; Drag forces; Droplet surfaces; Drops and bubbles; Dynamic contacts; Impact system; Legendre polynomials; Liquid pool; Surface craters; Viscous liquids, Air, bubble; capillary wave; deformation; drag; droplet; immiscible fluid
Department/Centre: Division of Mechanical Sciences > Mechanical Engineering
Date Deposited: 16 Feb 2023 04:43
Last Modified: 16 Feb 2023 04:43
URI: https://eprints.iisc.ac.in/id/eprint/80294

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