Stable-streamlined cavities following the impact of non-superhydrophobic spheres on water.

Ivan Uriev Vakarelski, Aditya Jetly, Sigurdur T Thoroddsen

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


The formation of a stable-streamlined gas cavity following the impact of a heated Leidenfrost sphere on a liquid surface or a superhydrophobic sphere on water is a recently demonstrated phenomenon. A sphere encapsulated in a teardrop-shaped gas cavity was found to have near-zero hydrodynamic drag due to the self-adjusting streamlined shape and the free-slip boundary condition on the cavity interface. Here we show that such cavities can as well be formed following water impact from a sufficient height of non-superhydrophobic spheres with water contact angles between >30° and 120°. In this case the streamlined cavity is attached just above the sphere's equator, instead of entirely wrapping the sphere. Nevertheless, this sphere with attached cavity formation has near-zero drag and a predetermined free fall velocity in compliance with the Bernoulli law of potential flow. The effect of surfactant addition to the water solution is investigated. The shape and fall velocity of a sphere with streamlined cavity formation were unaffected by the addition of low surface modulus synthetic surfactants, but were destabilised when solutions containing high surface modulus surfactants, such as soaps, were used.
Original languageEnglish (US)
Pages (from-to)6278-6287
Number of pages10
JournalSoft matter
Issue number31
StatePublished - 2019

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We acknowledge Dr Krastanka Marinova for advice on thesurfactant solution formulation. This work was supported by King Abdullah University of Science and Technology (KAUST).


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