Capillary-gravity waves generated by a slow moving object.
We investigate theoretically and experimentally the capillary-gravity waves created by a small object moving steadily at the water-air interface along a circular trajectory. It is well established that, for straight uniform motion, no steady waves appear at velocities below the minimum phase velocity c(min)=23 cm s(-1). We demonstrate that no such velocity threshold exists for a steady circular motion, for which, even for small velocities, a finite wave drag is experienced by the object. This wave drag originates from the emission of a spiral-like wave pattern. Our results are in good agreement with direct experimental observations of the wave pattern created by a circularly moving needle in contact with water. Our study leads to new insights into the problem of animal locomotion at the water-air interface.
Chepelianskii
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Laboratoire Physico-Chimie Théorique, UMR CNRS Gulliver 7083, ESPCI, 10 rue Vauquelin, 75005 Paris, France.
Chevy
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Raphaël
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