Motivation:

  • Skin friction drag contributes to 60-70% of the total drag for a cargo ship, 80% for a tanker and 90% for underwater vehicles.
  • Shipping alone accounts for 8.5% of the global oil supply and 3.3% of CO2 emissions.
  • Just 16 of the world’s largest ships can produce as much lung-clogging sulphur pollution as all the world’s car.
  • Superhydrophobic (SHPo) surface is able to produce significant drag reduction to reduce fuel consumption and increase speed of the ships.

Milestones:

 

 

 

 2006: Large slip was obtained on "Nanoturf" (Published in PRL)

 

 

 

 2008: Design rules of SHPo surface drag reduction in laminar flow (Published in PRL)

 

 

 

 2011: First sustainable "active" SHPo surface for practical drag reduction (Published in PRL, highlighted in Nature)

 

 

 

 2014: 75% drag reduction in turbulent flow !! (Published in JFM)

 

 

 

 2014: SHPo states could last infinitely underwater!! But don`t be over-optimistic (Published in PRL)

Next ?

 

 

 

 

Next: Practical drag (power) reduction for marine vessels

Journal Publication:

  • M. Xu, G. Sun, and C.-J. Kim, "Infinite Lifetime of Underwater Superhydrophobic States", Physical Review Letters, vol. 113, p. 136103, 09/25/ 2014.
  • H. Park, G. Sun, and C.-J. Kim, "Superhydrophobic turbulent drag reduction as a function of surface grating parameters", Journal of Fluid Mechanics, vol. 747, pp. 722-734, 2014.
  • C. Lee and C.-J. Kim, "Wetting and Active Dewetting Processes of Hierarchically Constructed Superhydrophobic Surfaces Fully Immersed in Water", Journal of Microelectromechanical Systems, vol. 21, pp. 712-720, Jun 2012.
  • C. Lee and C. J. Kim, "Influence of Surface Hierarchy of Superhydrophobic Surfaces on Liquid Slip", Langmuir, vol. 27, pp. 4243-4248, Apr 5 2011.
  • C. Lee and C.-J. Kim, "Underwater Restoration and Retention of Gases on Superhydrophobic Surfaces for Drag Reduction", Physical Review Letters, vol. 106, p. 14502, 2011.
  • C. Lee and C.-J. Kim, "Maximizing the giant liquid slip on superhydrophobic microstructures by nanostructuring their sidewalls", Langmuir, vol. 25, pp. 12812-12818, 2009.
  • C. Lee, C.-H. Choi, and C.-J. Kim, "Structured surfaces for a giant liquid slip", Physical Review Letters, vol. 101, p. 64501, 2008.
  • C.-H. Choi and C.-J. Kim, "Large slip of aqueous liquid flow over a nanoengineered superhydrophobic surface", Physical Review Letters, vol. 96, p. 066001, Feb 17 2006.