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METHODE NUMERIQUE HYBRIDE POUR L'ETUDE DU RAYONNEMENT ACOUSTIQUE D'ECOULEMENTS TURBULENTS PARIETAUX

Abstract : An hybrid approach is developed for the prediction of acoustic radiation of wall-bounded unsteady flows, and its application on the configuration of a blunt flat plate is performed. Aerodynamic data are obtained through a direct numerical simulation, assuming an incompressible flow. The no-slip condition at the wall is modelled with an external force-field ; this virtual boundary method is especially tailored for complex geometries, and is original in the field of aeroacoustics. Its mechanism as a feedback control system is analysed, which allows to decrease the penalty on the time-step. The behavior of the method when sharp edges are present is also studied. The 3D turbulent channel flow was simulated for the validation, and comparisons with the litterature show a good agreement. The scheme giving access to the hydrodynamic pressure is also detailed, in order to valid the fluctuating pressure fields used as input data for the acoustic calculation. The application to the 2D configuration of the blunt flat plate shows that it is difficult to obtain a perfectly converged flow. The processes of vortex shedding and flapping of the shear layer generated at the leading edge, as well as statistic properties of the turbulence are analysed. The acoustic radiation is computed through the application of the Curle's analogy, implemented with an advanced time approach. The acoustic fields show that volumic source terms radiate more than the surfacic source terms. For a compact source, the maximum of sound intensity is observed in the direction around 60 degrees downstream, as a consequence of the conjugated effect of the volumic term associated with the shear stress and the longitudinal volumic term. For a non-compact source, an important influence is observed when the retarded time are taken into account, showing an enhancement of the radiation of the longitudinal volumic term downstream.
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Contributor : Florent Margnat <>
Submitted on : Monday, April 24, 2006 - 4:26:39 PM
Last modification on : Monday, October 26, 2020 - 4:38:01 PM
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  • HAL Id : tel-00012176, version 1

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Florent Margnat. METHODE NUMERIQUE HYBRIDE POUR L'ETUDE DU RAYONNEMENT ACOUSTIQUE D'ECOULEMENTS TURBULENTS PARIETAUX. Mécanique [physics.med-ph]. Université de Poitiers, 2005. Français. ⟨tel-00012176⟩

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