### Abstract

Droplets can be levitated by their own vapour when placed onto a superheated plate (the Leidenfrost effect). It is less known that the Leidenfrost effect can likewise be observed over a liquid pool (superheated with respect to the drop), which is the study case here. Emphasis is placed on an asymptotic analysis in the limit of small evaporation numbers, which indeed proves to be a realistic one for millimetric-sized drops (i.e. where the radius of the drop is of the order of the capillary length). The global shapes are found to resemble 'superhydrophobic drops' that follow from the equilibrium between capillarity and gravity. However, the morphology of the thin vapour layer between the drop and the pool is very different from that of classical Leidenfrost drops over a flat rigid substrate, and exhibits different scaling laws. We determine analytical expressions for the vapour thickness as a function of temperature and material properties, which are confirmed by numerical solutions. Surprisingly, we show that deformability of the pool suppresses the chimney instability of Leidenfrost drops.

Original language | English |
---|---|

Pages (from-to) | 1157-1189 |

Number of pages | 33 |

Journal | Journal of fluid mechanics |

Volume | 863 |

DOIs | |

Publication status | Published - 25 Mar 2019 |

### Fingerprint

### Keywords

- UT-Hybrid-D
- drops
- lubrication theory
- condensation/evaporation

### Cite this

*Journal of fluid mechanics*,

*863*, 1157-1189. https://doi.org/10.1017/jfm.2018.1025

}

*Journal of fluid mechanics*, vol. 863, pp. 1157-1189. https://doi.org/10.1017/jfm.2018.1025

**Asymptotic theory for a Leidenfrost drop on a liquid pool.** / Van Limbeek, Michiel A.J. (Corresponding Author); Sobac, Benjamin; Rednikov, Alexey; Colinet, Pierre; Snoeijer, Jacco H.

Research output: Contribution to journal › Article › Academic › peer-review

TY - JOUR

T1 - Asymptotic theory for a Leidenfrost drop on a liquid pool

AU - Van Limbeek, Michiel A.J.

AU - Sobac, Benjamin

AU - Rednikov, Alexey

AU - Colinet, Pierre

AU - Snoeijer, Jacco H.

N1 - Cambridge deal

PY - 2019/3/25

Y1 - 2019/3/25

N2 - Droplets can be levitated by their own vapour when placed onto a superheated plate (the Leidenfrost effect). It is less known that the Leidenfrost effect can likewise be observed over a liquid pool (superheated with respect to the drop), which is the study case here. Emphasis is placed on an asymptotic analysis in the limit of small evaporation numbers, which indeed proves to be a realistic one for millimetric-sized drops (i.e. where the radius of the drop is of the order of the capillary length). The global shapes are found to resemble 'superhydrophobic drops' that follow from the equilibrium between capillarity and gravity. However, the morphology of the thin vapour layer between the drop and the pool is very different from that of classical Leidenfrost drops over a flat rigid substrate, and exhibits different scaling laws. We determine analytical expressions for the vapour thickness as a function of temperature and material properties, which are confirmed by numerical solutions. Surprisingly, we show that deformability of the pool suppresses the chimney instability of Leidenfrost drops.

AB - Droplets can be levitated by their own vapour when placed onto a superheated plate (the Leidenfrost effect). It is less known that the Leidenfrost effect can likewise be observed over a liquid pool (superheated with respect to the drop), which is the study case here. Emphasis is placed on an asymptotic analysis in the limit of small evaporation numbers, which indeed proves to be a realistic one for millimetric-sized drops (i.e. where the radius of the drop is of the order of the capillary length). The global shapes are found to resemble 'superhydrophobic drops' that follow from the equilibrium between capillarity and gravity. However, the morphology of the thin vapour layer between the drop and the pool is very different from that of classical Leidenfrost drops over a flat rigid substrate, and exhibits different scaling laws. We determine analytical expressions for the vapour thickness as a function of temperature and material properties, which are confirmed by numerical solutions. Surprisingly, we show that deformability of the pool suppresses the chimney instability of Leidenfrost drops.

KW - UT-Hybrid-D

KW - drops

KW - lubrication theory

KW - condensation/evaporation

U2 - 10.1017/jfm.2018.1025

DO - 10.1017/jfm.2018.1025

M3 - Article

VL - 863

SP - 1157

EP - 1189

JO - Journal of fluid mechanics

JF - Journal of fluid mechanics

SN - 0022-1120

ER -