Rolling stones: The motion of a sphere down an inclined plane coated with a thin liquid film
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McKinley_Rolling Stones.pdf
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Author(s)
Bico, Jose
Ashmore-Chakrabarty, J.
Stone, H. A.
McKinley, Gareth H
Date Issued
August 2009
Journal
Physics of Fluids
Publisher
American Institute of Physics
Citation
Bico, J. et al. “Rolling stones: The motion of a sphere down an inclined plane coated with a thin liquid film.” Physics of Fluids 21.8 (2009): 082103-8. © 2009 American Institute of Physics
Version
Final published version
Abstract
A spherical bead deposited on a smooth tilted dry plane wall rolls down the slope under the uniform acceleration of gravity. We describe an analogous experiment conducted using a plane wall that is coated with a thin layer (of order 50–100 μm) of a viscous liquid. The steady motion of the sphere under gravity involves a combination of rotation and sliding. We examine the dependence of the experimentally observed steady translational and rotational speeds on the physical parameters in the system. In particular, the interplay between viscous forces and interfacial forces leads to nontrivial exponents for the scaling of the speeds with the characteristics of the sphere and the viscous liquid. The overhang situation, in which the sphere rolls down the underside of an inclined lubricated plane, is also examined. In this case, the steady motion is still observed for a certain range of angles and bead sizes; that is, the sphere does not always detach from the surface. The adhesive force arises dynamically from the motion of the sphere and can exceed classical quasistatic capillary forces. Such a force should also play a role in other problems of lubrication mechanics such as humid granular flows.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology. Hatsopoulos Microfluids Laboratory
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1063/1.3207884
