Leidenfrost vapour layer moderation of the drag crisis and trajectories of superhydrophobic and hydrophilic spheres falling in water
KAUST DepartmentClean Combustion Research Center
Physical Sciences and Engineering (PSE) Division
Mechanical Engineering Program
High-Speed Fluids Imaging Laboratory
MetadataShow full item record
AbstractWe investigate the dynamic effects of a Leidenfrost vapour layer sustained on the surface of heated steel spheres during free fall in water. We find that a stable vapour layer sustained on the textured superhydrophobic surface of spheres falling through 95 °C water can reduce the hydrodynamic drag by up to 75% and stabilize the sphere trajectory for the Reynolds number between 104 and 106, spanning the drag crisis in the absence of the vapour layer. For hydrophilic spheres under the same conditions, the transition to drag reduction and trajectory stability occurs abruptly at a temperature different from the static Leidenfrost point. The observed drag reduction effects are attributed to the disruption of the viscous boundary layer by the vapour layer whose thickness depends on the water temperature. Both the drag reduction and the trajectory stabilization effects are expected to have significant implications for development of sustainable vapour layer based technologies. © the Partner Organisations 2014.
SponsorsWe acknowledge G. D. Li from the KAUST Solar and Photovoltaics Research Center for assisting in the water tank and heater device design, and the KAUST Machine Workshop for the support in setting the experiments. This work is support in part by an Australian Research Council Discovery Project Grant to DYCC.
PublisherRoyal Society of Chemistry (RSC)
- Drag crisis moderation by thin air layers sustained on superhydrophobic spheres falling in water.
- Authors: Jetly A, Vakarelski IU, Thoroddsen ST
- Issue date: 2018 Feb 28
- Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces.
- Authors: Vakarelski IU, Patankar NA, Marston JO, Chan DY, Thoroddsen ST
- Issue date: 2012 Sep 13
- Sustained drag reduction in a turbulent flow using a low-temperature Leidenfrost surface.
- Authors: Saranadhi D, Chen D, Kleingartner JA, Srinivasan S, Cohen RE, McKinley GH
- Issue date: 2016 Oct
- Drag Moderation by the Melting of an Ice Surface in Contact with Water.
- Authors: Vakarelski IU, Chan DY, Thoroddsen ST
- Issue date: 2015 Jul 24
- Internal and External Flow over Laser-Textured Superhydrophobic Polytetrafluoroethylene (PTFE).
- Authors: Ahmmed KM, Patience C, Kietzig AM
- Issue date: 2016 Oct 12