Influence of gravity on the sliding angle of water drops on nanopillared superhydrophobic surfaces

Molecular dynamics (MD) simulations were used to study the effects of gravity, solid surface energy, and the fraction of water–solid interface area on the water droplet sliding angles on nanopillared surfaces. To effectively simulate the influence of gravity on drop sliding, we developed a protocol in which we scale the value of gravitational acceleration used in our simulations according to the Bond number (Bo). In this way, we approximate the behavior of drops larger than we can effectively simulate using MD. The sliding angle decreased with an increase in Bo, while it increased with an increase in the liquid–solid surface interaction. The sliding angles exhibit a minimum with an increase in the fraction of water–solid interface area, due to meniscus formation at high fractions. Trends predicted by our model are in agreement with experiment. Using our model, we investigated the mechanisms of droplet movement along nanopillared surfaces. Depending on the pinning state of the droplets at equilibrium, either the advancing or the receding contact angle initiates motion. Moreover, the minimum dynamic advancing and receding contact angles of drops with gravity are close to the static contact angle and the intrinsic contact angle, respectively, while the maxima of both angles are as large as 180°. We find that the drops move through a combination of sliding and rolling, in agreement with experiment. Our studies offer clarity to conflicting experimental reports and present new results awaiting experimental confirmation.

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, copyright © 2020 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see


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Work Title Influence of gravity on the sliding angle of water drops on nanopillared superhydrophobic surfaces
Open Access
  1. Hao Li
  2. Tianyu Yan
  3. Kristen A. Fichthorn
License In Copyright (Rights Reserved)
Work Type Article
  1. American Chemical Society (ACS)
Publication Date August 3, 2020
Publisher Identifier (DOI)
  1. 10.1021/acs.langmuir.0c01597
  1. Langmuir
Deposited June 17, 2022




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Work History

Version 1

  • Created
  • Added Li_revised-1.pdf
  • Added Creator Hao Li
  • Added Creator Tianyu Yan
  • Added Creator Kristen A. Fichthorn
  • Published
  • Updated Creator Kristen A. Fichthorn
  • Updated