Self-determined shapes and velocities of giant near-zero drag gas cavities
Ivan U Vakarelski, Evert Klaseboer, Aditya Jetly, Mohammad M Mansoor, Andres A Aguirre-Pablo, Derek YC Chan, Sigurdur T Thoroddsen
SCIENCE ADVANCES | AMER ASSOC ADVANCEMENT SCIENCE | Published : 2017
Minimizing the retarding force on a solid moving in liquid is the canonical problem in the quest for energy saving by friction and drag reduction. For an ideal object that cannot sustain any shear stress on its surface, theory predicts that drag force will fall to zero as its speed becomes large. However, experimental verification of this prediction has been challenging. We report the construction of a class of self-determined streamlined structures with this free-slip surface, made up of a teardrop-shaped giant gas cavity that completely encloses a metal sphere. This stable gas cavity is formed around the sphere as it plunges at a sufficiently high speed into the liquid in a deep tank, prov..View full abstract
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Awarded by Australian Research Council
This work was supported by the King Abdullah University of Science and Technology. D.Y.C.C. was supported by the Australian Research Council through Discovery Project grant no. DP170100376. Author contributions: I.U.V.conceived the research and designed the experiments. I.U.V., A.J., M.M.M., and A.A.A.-P. carried out the experiments. S.T.T. supervised the project, developed the image processing, and discussed the theoretical approach. E.K. and D.Y.C.C. undertook the theoretical interpretation and calculations.