Spreading of droplets impacting different wettable surfaces at a Weber number close to zero

Xin Liu, Xuan Zhang, Jingchun Min*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

67 Citations (Scopus)

Abstract

Six different surfaces ranging from superhydrophilic to superhydrophobic were fabricated. Droplet impact experiments were conducted on these surfaces with water droplets 2.25 mm in diameter at a Weber number close to zero to study the effects of surface wettability on the impact process and post-impact oscillation. Droplet impact on all surfaces, except for superhydrophobic surfaces, is dominated by a spreading stage and no evident retraction is observed. Using the inertia-capillarity time tc = ρR03/σ as characteristic time, the spreading stage on all surfaces at We < 0.5 was calculated to be 2.25 ± 0.11tc; further, it could be divided into inertial and viscous spreading stages at 1 ± 0.11tc based on droplet height evolution. A semi-empirical correlation for calculating the evolution of spreading factors on different surfaces was fitted by a piecewise exponential function using experimental data, and a deviation of ±20% was observed between the fitted and experimental data.

Original languageEnglish
Pages (from-to)495-503
Number of pages9
JournalChemical Engineering Science
Volume207
DOIs
Publication statusPublished - 2 Nov 2019
Externally publishedYes

Keywords

  • Advancing contact angle
  • Droplet spreading
  • Low Weber number
  • Surface wettability

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