Leidenfrost levitation of a spherical particle above a liquid bath: evolution of the vapour-film morphology with particle size
File(s)EJAMfinal.pdf (954.9 KB)
Accepted version
Author(s)
Brandao, Rodolfo
Schnitzer, Ory
Type
Journal Article
Abstract
We consider a spherical particle levitating above a liquid bath owing to the Leidenfrost effect, where the vapour of either the bath or sphere forms an insulating film whose pressure supports the sphere’s weight. Starting from a reduced formulation based on a lubrication-type approximation, we use matched asymptotics to describe the morphology of the vapour film assuming that the sphere is small relative to the capillary length (small Bond number) and that the densities of the bath and sphere are comparable. We find that this regime is comprised of two formally infinite sequences of distinguished limits which meet at an accumulation point, the limits being defined by the smallness of an intrinsic evaporation number relative to the Bond number. These sequences of limits reveal a sur16 prisingly intricate evolution of the film morphology with increasing sphere size. Initially, the vapour film transitions from a featureless morphology, where the thickness profile is parabolic, to a neck-bubble morphology, which consists of a uniform-pressure bubble bounded by a narrow and much thinner annular neck. Gravity effects then become im20 portant in the bubble leading to sequential formation of increasingly smaller neck-bubble pairs near the symmetry axis. This process terminates when the pairs closest to the sym metry axis become indistinguishable and merge. Subsequently, the inner section of that merger transitions into a uniform-thickness film that expands radially, gradually squish24 ing larger and larger neck-bubble pairs into a region of localised oscillations sandwiched between the uniform film and what remains of the bubble whose radial extent is presently comparable to the uniform film; the neck-bubble pairs farther from the axis remain es sentially intact. Ultimately, the uniform film gobbles up the largest outermost bubble, whereby the morphology simplifies to a uniform film bounded by localised oscillations. Overall, the asymptotic analysis describes the continuous evolution of the vapour film from a neck-bubble morphology typical of a Leidenfrost drop levitating above a flat solid substrate to a uniform-film morphology which resembles that in the case of a large liquid drop levitating above a liquid bath.
Date Issued
2022-12-01
Date Acceptance
2022-01-06
Citation
European Journal of Applied Mathematics, 2022, 33 (6), pp.1117-1169
ISSN
0956-7925
Publisher
Cambridge University Press
Start Page
1117
End Page
1169
Journal / Book Title
European Journal of Applied Mathematics
Volume
33
Issue
6
Copyright Statement
© The Author(s), 2022. Published by Cambridge University Press. This article has been published in a revised form in European Journal of Applied Mathematics https://doi.org/10.1017/S095679252200002X. This version is free to view and download for private research and study only. Not for re-distribution, re-sale or use in derivative works.
Identifier
https://www.cambridge.org/core/journals/european-journal-of-applied-mathematics/article/leidenfrost-levitation-of-a-spherical-particle-above-a-liquid-bath-evolution-of-the-vapourfilm-morphology-with-particle-size/5024A97482E3C5F187BEC3746607BFB8
Publication Status
Published
Date Publish Online
2022-02-17