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The rolling up of sheets in a steady flow

Published online by Cambridge University Press:  01 September 2006

LIONEL SCHOUVEILER
Affiliation:
Institut de Recherche sur les Phénomènes Hors Équilibre, 49 rue Joliot-Curie, BP 146, F-13384 Marseille Cedex 13, France
AREZKI BOUDAOUD
Affiliation:
Laboratoire de Physique Statistique, Ecole Normale Supérieure, 24 rue Lhomond, F-75231 Paris Cedex 05, France

Abstract

The mechanism of reconfiguration of broad leaves subjected to wind loading is investigated. Circular plastic sheets cut along a radius are immersed in a water flow. They roll up into cones when held at their centres. The opening angle of the cone and the drag force exerted on the sheet are measured as a function of the flow velocity and of the sheet bending rigidity. The cone becomes sharper when the velocity increases or when the sheet stiffness decreases; the reconfiguration leads to a decrease in the drag coefficient. Scaling laws are derived from the mechanical equilibrium of the sheets – the balance between form drag and elastic forces – and the experimental data collapse onto master curves. Two models for the pressure field yield theoretical curves in semi-quantitative agreement with the experiments.

Type
Papers
Copyright
© 2006 Cambridge University Press

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