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Foliage mechanics in wind: multi-scale approach and biological consequences

Laboratoire d'Hydrodynamique, Ecole Polytechnique, Palaiseau
le 10/04/2015 à 14:15
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A wind gust and the leaves already move. On land, the Beaufort scale is defined through the observation of foliage motion. The leaves motion in wind is the result of fluidstructure interaction between the tree and wind. The effect of wind on the tree is on the one hand static, the leaves reconfigure, change their orientation and gather themselves, and on the other hand dynamic, when leaves and branches move. Those movements change the plant biology through light interception, heat and gas exchange, water retention by the foliage, etc. However there is no mechanical description of the foliage movements in wind. Thus the variations of biological quantities due to foliage movements in wind are usually not taken into account in functional-structural plants models.

Those mechanical effects are explored at the leaf scale highlighting the static reconfiguration and the dynamic flutter of leaves. These results at the leaf scale are broadenned to the whole foliage using statistical tools. Eventually, the models of foliage movement are used to compute global biological traits such as light interception or perceptive effects such as the dynamic motion of the foliage.