A fast numerical framework for acoustic scattering by 3d poroelastic plates

Resumo

© 2015, American Institute of Aeronautics and Astronautics Inc, AIAA. All Rights Reserved.We present a fast numerical framework to compute the acoustic scattering by 3D poroe-lastic plates. A boundary element method (BEM) is applied to solve the Helmholtz equation subjected to boundary conditions related to the vibration of the plate. This analysis is performed by rewriting the boundary conditions in terms of the structural modes of the plate, which allows a direct solution of the coupled problem. In order to accelerate the solution of the large dense linear systems from the BEM formulation, a wideband adaptive fast multipole method (FMM) is employed. A pseudo-spectral method is applied to compute the structural modes of the plate. A parametric study is carried out for a 3D acoustic scattering problem where a model source is placed close to the trailing edge of a plate with finite span and chord. The current study presents results for plates with a clamped leading edge and free trailing and lateral edges. Results are shown for different configurations including rigid, porous-rigid, impermeable-elastic and poroelastic plates. The effects of plate aspect ratio are evaluated for different ranges of acoustic and plate vibration frequencies. A study of trailing edge scattering by 2D and 3D acoustic sources is also presented. It is shown that the combination of elasticity and porosity can reduce the intensity of the far-field sound scattered by turbulence near an edge of the plate.