Significant and stable drag reduction with air rings confined by alternated superhydrophobic and hydrophilic strips

Haibao Hu, Jun Wen, Luyao Bao, Laibing Jia, Dong Song, Baowei Song, Guang Pan, Michele Scaraggi, Daniele Dini, Qunji Xue, Feng Zhou

Research output: Contribution to journalArticle

58 Citations (Scopus)
12 Downloads (Pure)

Abstract

Superhydrophobic surfaces have the potential to reduce the viscous drag of liquids by significantly decreasing friction at a solid-liquid interface due to the formation of air layers between solid walls and interacting liquids. However, the trapped air usually becomes unstable due to the finite nature of the domain over which it forms. We demonstrate for the first time that a large surface energy barrier can be formed to strongly pin the three-phase contact line of air/water/solid by covering the inner rotor of a Taylor-Couette flow apparatus with alternating superhydrophobic and hydrophilic circumferential strips. This prevents the disruption of the air layer, which forms stable and continuous air rings. The drag reduction measured at the inner rotor could be as much as 77.2%. Moreover, the air layers not only significantly reduce the strength of Taylor vortexes but also influence the number and position of the Taylor vortex pairs. This has strong implications in terms of energy efficiency maximization for marine applications and reduction of drag losses in, for example, fluid transport in pipelines and carriers.
Original languageEnglish
Article numbere1603288
Number of pages9
JournalScience Advances
Volume3
Issue number9
DOIs
Publication statusPublished - 1 Sep 2017

Keywords

  • superhydrophobic
  • friction
  • drag

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