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Home page > Seminars > Previous seminars > Seminars 2011 > MSC Seminar 2011 May 2nd at 11:30. Élie Raphaël (Laboratoire Gulliver, ESPCI) : Moving in circle.

Séminaire MSC 2 mai 2011 à 11h30. Élie Raphaël (Laboratoire Gulliver, ESPCI) : Moving in circle

Sauf mention contraire, les séminaires et les soutenances se déroulent à 11h30 en salle 454A du bâtiment Condorcet.


It is generally believed that in order to generate waves, a small object (like an insect) moving at the air-water surface must exceed the minimum wave speed (about 23 centimeters per second). We show that this result is only valid for a rectilinear uniform motion, an assumption often overlooked in the literature. In the case of a steady circular motion (a situation of particular importance for the study of whirligig beetles), we demonstrate that no such velocity threshold exists and that even at small velocities a finite wave drag is experienced by the object. This wave drag originates from the emission of a spiral-like wave pattern. The results presented should be important for a better understanding of the propulsion of water-walking insects. For example, it would be very interesting to know if whirligig beetles can take advantage of such spirals for echolocation purposes.


Contact : Équipe séminaires / Seminar team - Published on / Publié le 7 février 2011


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