Quelques problèmes d’optimisation de trainée : De la propulsion par rame à la collecte d’aérosol

Abstract : The rowing propulsion results from the compensation between water resistance on the hull and the attachment of the oars in the water. For fog collection using nets, the dynamics of water harvesting results from the effects of air resistance on the droplets combined with flow disturbances at the net level. In this thesis, - centered on the fluid / structure interactions - we sought to optimize the efficiency (propulsion and collection) from the hydro and aerodynamic point of view. For this, we relied on model experiments (Robot rowing boats, mist wind tunnel) to be placed in controllable laboratory conditions and to overcome human and climatic bias.In the first part on rowing, we showed what was the optimal oars length for propulsion. Then we were interested in the effect of the phase shift between the rowers and showed that a perfect synchronization makes it possible to obtain a maximum speed. Finally, we carried out an empirical and experimental study on the shapes (aspect ratio and symmetry) of optimal hulls. The second part deals with the collection of water using mist nets, which began with a study of the impact of the drops on a mesh (fiber) of the net and then within a complete net. Finally, we studied the effect of fiber elasticity and drainage on collection. This study has highlighted the importance of fiber wetting properties on net collection and design.
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Romain Labbe. Quelques problèmes d’optimisation de trainée : De la propulsion par rame à la collecte d’aérosol. Mécanique des fluides [physics.class-ph]. Université Paris-Saclay, 2018. Français. ⟨NNT : 2018SACLX080⟩. ⟨tel-02270662⟩

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