Cavity formation by the impact of Leidenfrost spheres

J. O. Marston, I. U. Vakarelski, S. T. Thoroddsen

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

We report observations of cavity formation and subsequent collapse when a heated sphere impacts onto a liquid pool. When the sphere temperature is much greater than the boiling point of the liquid, we observe an inverted Leidenfrost effect where the sphere is encompassed by a vapour layer that prevents physical contact with the liquid. This creates the ultimate non-wetting scenario during sphere penetration through a free surface, producing very smooth cavity walls. In some cases during initial entry, however, the liquid contacts the sphere at the equator, leading to the formation of a dual cavity structure. For cold sphere impacts, where a contact line is observed, we reveal details of the contact line pinning, which initially forms a sawtooth pattern. We also observe surface waves on the cavity interface for cold spheres. We compare our experimental results to previous studies of cavity dynamics and, in particular, the influence of hydrophobicity on the entry of the sphere.

Original languageEnglish
Pages (from-to)465-488
Number of pages24
JournalJournal of Fluid Mechanics
Volume699
DOIs
StatePublished - May 25 2012

Keywords

  • cavitation
  • contact lines
  • transition to turbulence

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