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Etudes des structures spatio-temporelles dans un sillage de mât conditionnées par l'action commune des vagues et des courants.

Abstract : The various experiments carried out have laid emphasis on the study of hydrodynamic spatio-temporal structures found in an offshore wind turbine’s mast, coupled to a cylinder, which will later on be used at the Courseulles-sur-Mer wind farm. The hydrodynamic analysis focused on the synchronization phenomenon between regular waves and the Von Karman Street generated by a current, behind two different vertical cylinders. A diagram showing the different synchronization regimes with respect to the frequencies of the waves and the amplitudes studied, has been drawn. In addition to the results obtained with regular waves, the synchronization phenomenon has also been analysed using irregular waves. In the case of irregular waves, the phase diffusion coefficient, K, has been used to explain the different frequency synchronization observed. After having studied the synchronization phenomenon, tests were carried out on the study of sediment transport (scour and ripples) under the effect of different types of flows in an environment close to a vertical cylinder. In parallel to the laboratory experiments, a numerical study has also been conducted by studying the DNS (Direct Numerical Simulation) of a steady flow of current around a vertical cylinder. In addition to that a more complicated flow of a steady current around a network of cylinders comprising of a series of 4 cylinders arranged in 2 rows (representing a network of wind turbine masts) have also been observed and analysed. After having studied the flow made up by a steady current, the olafoam solver was used to apply a flow made up of both currents and waves in an obstacle free environment with a smooth floor. The numerical results obtained close to the free surface have been found to fairly agree with the findings of other related studies conducted. We observed a reduction in the intensity of the surface current when the waves and the current propagate in the same direction.
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Submitted on : Monday, March 26, 2018 - 4:07:07 PM
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  • HAL Id : tel-01743674, version 1

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Hans Gunnoo. Etudes des structures spatio-temporelles dans un sillage de mât conditionnées par l'action commune des vagues et des courants.. Mécanique des fluides [physics.class-ph]. Normandie Université, 2017. Français. ⟨NNT : 2017NORMC264⟩. ⟨tel-01743674⟩

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