Leidenfrost Vapor Layers Reduce Drag without the Crisis in High Viscosity Liquids.
The drag coefficient C_{D} of a solid smooth sphere moving in a fluid is known to be only a function of the Reynolds number Re and diminishes rapidly at the drag crisis around Re∼3×10^{5}. A Leidenfrost vapor layer on a hot sphere surface can trigger the onset of the drag crisis at a lower Re. By using a range of high viscosity perfluorocarbon liquids, we show that the drag reduction effect can occur over a wide range of Re, from as low as ∼600 to 10^{5}. The Navier slip model with a viscosity dependent slip length can fit the observed drag reduction and wake shape.
Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Ivan U
IU
Vakarelski
Department of Chemical and Biomolecular Engineering, University of Melbourne, Parkville VIC 3010, Australia.|Mineral Resources, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton VIC 3169, Australia.
Joseph D
JD
Berry
School of Mathematics and Statistics, University of Melbourne, Parkville 3010, Australia.|Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn 3122, Australia.
Derek Y C
DY
Chan
Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Sigurdur T
ST
Thoroddsen