A possibility of saturating Rayleigh-Taylor instability in a thin liquid film on the underside of a substrate in the gravity field by harmonic vibration of the substrate was recently investigated [E. Sterman-Cohen, M. Bestehorn, and A. Oron, Phys. Fluids 29, 052105 (2017); Erratum, Phys. Fluids 29, 109901 (2017)]. In the present work, we investigate the feasibility of creating a directional flow of the fluid in a film in the Rayleigh-Taylor configuration and controlling its flow rate by applying a two-frequency tangential forcing to the substrate. It is shown that in this situation, a ratchet flow develops, and the dependence of its flow rate on the vibration frequency, amplitude, its periodicity, and asymmetry level is investigated for water and silicone-oil films. A cause for the emergence of symmetry-breaking and an ensuing flow in a preferred direction is discussed. Some aspects of a ratchet flow in a liquid film placed on top of the substrate are discussed as well. A comparison with the case of a neglected fluid inertia is made, and the differences are explained.
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February 2018
Research Article|
February 07 2018
Ratchet flow of thin liquid films induced by a two-frequency tangential forcing
Elad Sterman-Cohen;
Elad Sterman-Cohen
1
Department of Mechanical Engineering, Technion-Israel Institute of Technology
, Haifa 32000, Israel
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Michael Bestehorn;
Michael Bestehorn
2
Department of Theoretical Physics, Brandenburg University of Technology
, 03044 Cottbus, Germany
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Alexander Oron
Alexander Oron
1
Department of Mechanical Engineering, Technion-Israel Institute of Technology
, Haifa 32000, Israel
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Physics of Fluids 30, 022101 (2018)
Article history
Received:
October 24 2017
Accepted:
January 18 2018
Citation
Elad Sterman-Cohen, Michael Bestehorn, Alexander Oron; Ratchet flow of thin liquid films induced by a two-frequency tangential forcing. Physics of Fluids 1 February 2018; 30 (2): 022101. https://doi.org/10.1063/1.5010262
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