Numerical solution of acoustic scattering by finite perforated elastic plates.
We present a numerical method to compute the acoustic field scattered by finite perforated elastic plates. A boundary element method is developed to solve the Helmholtz equation subjected to boundary conditions related to the plate vibration. These boundary conditions are recast in terms of the vibration modes of the plate and its porosity, which enables a direct solution procedure. A parametric study is performed for a two-dimensional problem whereby a cantilevered perforated elastic plate scatters sound from a point quadrupole near the free edge. Both elasticity and porosity tend to diminish the scattered sound, in agreement with previous work considering semi-infinite plates. Finite elastic plates are shown to reduce acoustic scattering when excited at high Helmholtz numbersk0based on the plate length. However, at lowk0, finite elastic plates produce only modest reductions or, in cases related to structural resonance, an increase to the scattered sound level relative to the rigid case. Porosity, on the other hand, is shown to be more effective in reducing the radiated sound for lowk0. The combined beneficial effects of elasticity and porosity are shown to be effective in reducing the scattered sound for a broader range ofk0for perforated elastic plates.
Divisão de Engenharia Aeronáutica , Instituto Tecnológico de Aeronáutica, São José dos Campos , Sao Paulo 12228-900, Brazil.
A V G
0000-0003-4283-0232
AV
Cavalieri
Faculdade de Engenharia Mecânica , Universidade Estadual de Campinas , Campinas, Sao Paulo 13083-860, Brazil.
W R
0000-0001-8207-8466
WR
Wolf
Department of Mechanical Engineering and Mechanics , Lehigh University, Bethlehem , PA 18015-3085, USA.
J W
0000-0002-0746-7661
JW
Jaworski
acoustic scattering; aeroacoustics; fluid–structure interaction