Sketch of the experimental setup.
Sequential snapshots of a typical bouncing drop on the flat oscillating surface (f = 60 Hz, Γ = 8.7). Each image is acquired in 1 ms exposure, and with 1/600 s time interval.
Horizontal trajectory of a gliding drop. It bounces back and forth around two ends of the container (f = 60 Hz, Γ = 10.6).
The distortion of the surface capillary wave is found strong correlation with the speed of the “glider” (f = 60 Hz, Γ = 10.6). (a) Images of the drop at initial position. (b) Images of the drop at 30 mm (at constant speed). (c) Schematic diagram of the effect of the distorted surface capillary wave. The net force from the impact-driven distorted surface wave is suspected to be the driving source to the drop. However, the impact also is the dissipation to the drop. (d) Curve fitting of the gliding speed of the drop.
The response of the gliding drop at different frequency driving. (a) The gliding speeds of the drop are different at f = 50, 55, and 60 Hz and Γ = 9.1, 9.7, 10.6, respectively. (b) The terminal speeds and the average speeds of the drop at different driving frequency. The drop obtains the maximum traveling speed at 65 Hz driving. (c) The responses of k and F are acquired from the fitting results at different driving frequency. They both show the maximum values at 70 Hz driving.
(a) Snapshot of a typical drop on the Faraday wave surface (f = 60 Hz, Γ = 11.25). (b) Spectrum analysis of the vertical position of the Faraday wave surface (f = 60 Hz, Γ = 10.8) (inset) vertical oscillation of the height of the Faraday wave surface. (c) Faraday threshold at different driving frequency.
Drops are found traveling and being trapped on the surface of the Faraday wave. (a) Horizontal trajectory of a traveling drop on the Faraday wave, where the nodes of the wave are indicated by dashed lines (f = 60 Hz, Γ = 11.4). (b) The drop is trapped around the node of the wave and bouncing on the alternatively changed slope of the wave surface. (c) Schematic diagram of the stability of the drop on the Faraday wave. The drop is stable around the nodes and unstable at the anti-nodes. (d) Phase diagram of the drop trajectory in (a).
Modulation of the traveling speed of the drop on the Faraday wave. (a) Horizontal trajectory of the drop on the Faraday wave. The speed of the drop decreases from v = 73 mm/s to v = 41 mm/s, while the amplitude of the wave is suddenly increased from Γ = 10.8 to Γ = 11.2. (b) The average speed of the drop keeps constant below the threshold and decreases rapidly above the threshold. The threshold of the Faraday wave is about Γ F = 10.7. (c) The average speed of the drop on the Faraday wave is found linearly decreasing with the increase of the wave amplitude.
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