Formation of a hidden cavity below droplets impacting on a granular substrate

Song-Chuan Zhao*, Rianne de Jong, Devaraj van der Meer

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

5 Citations (Scopus)
38 Downloads (Pure)


Droplet impact on a granular layer results in various morphologies of the liquid–grain mixture. Some are concentrated and highly curved, some are extended and flatter. No matter how the morphology looks from the top, it is generally believed that its bottom is tightly connected to the concavely deformed granular target. In this paper we report the discovery of a hidden cavity below a droplet residual, formed upon impact on packings of hydrophilic grains and exposed by X-ray tomography. Its occurrence in the parameter space is explored. We elucidate the mechanism leading to this counterintuitive phenomenon using a dual-curvature model and an energy criterion. This research may shed new light onto the ongoing discussion about the origin of the so-called fossilized raindrop impressions.
Original languageEnglish
Pages (from-to)59-72
JournalJournal of fluid mechanics
Publication statusPublished - 10 Dec 2019


  • UT-Hybrid-D
  • granular media
  • drops


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