Abstract
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 similar to 3 x 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 similar to 600 to 10(5). The Navier slip model with a viscosity dependent slip length can fit the observed drag reduction and wake shape.