Capillary-scale solid rebounds: experiments, modelling and simulations

Research output: Contribution to journalArticlepeer-review


  • Radu Cimpeanu
  • Isabelle Bauman
  • Annika MacEwen
  • Paul MIlewski
  • Daniel Harris

Colleges, School and Institutes

External organisations

  • University of Warwick
  • University of Bath
  • Brown University


A millimetre-size superhydrophobic sphere impacting on the free surface of a quiescent bath can be propelled back into the air by capillary effects and dynamic fluid forces, whilst transferring part of its energy to the fluid. We report the findings of a thorough investigation of this phenomenon, involving different approaches. Over the range from minimum impact velocities required to produce rebounds to impact velocities that cause the sinking of the solid sphere, we focus on the dependence of the coefficient of restitution, contact time and maximum surface deflection on the different physical parameters of the problem. Experiments, simulations and asymptotic analysis reveal trends in the rebound metrics, uncover new phenomena at both ends of the Weber number spectrum, and collapse the data. Direct numerical simulations using a pseudo-solid sphere successfully reproduce experimental data whilst also providing insight into flow quantities that are challenging to determine from experiments. A model based on matching the motion of a perfectly hydrophobic impactor to a linearised fluid free surface is validated against direct numerical simulations and used in the low-Weber-number regime. The hierarchical and cross-validated models in this study allow us to explore the entirety of our target parameter space within a challenging multi-scale system.

Bibliographic note

Publisher Copyright: © 2021 The Author(s). Published by Cambridge University Press.


Original languageEnglish
Article numberA17
Number of pages31
JournalJournal of Fluid Mechanics
Early online date9 Feb 2021
Publication statusPublished - 10 Apr 2021


  • capillary waves, computational methods, wave-structure interactions