Using A Dual-BEM Formulation To Model The
Sound Pressure Wavefield Provided By
Absorbing Thin Screens Attached To The Walls Of
A Duct
Author(s)
J. António, L. Godinho, P. Amado Mendes & A. Tadeu
Abstract
The modelling of the 2D sound pressure wavefield in the presence of thin
absorbing screens attached to the walls of a duct, assumed to be infinitely long,
is described in this paper. The simulation uses a frequency-domain Dual-BEM
(BEM/TBEM) formulation, which overcomes the thin-body difficulty that arises
with the classical BEM formulation. The sound absorption is simulated by
imposing impedance boundary conditions, which are applied in conjunction with
a Dual-BEM approach. The fundamental solutions used in the formulation allow
the solution to be obtained without discretizing the duct’s walls. Thus, only the
boundary of each absorbing screen attached to the duct’s walls is modelled,
which makes the proposed formulation efficient even at high excitation
frequencies. The hypersingular integrals that result from the implementation of
the TBEM are computed analytically. The formulation is used to compare results
obtained with absorbing screens with those obtained with rigid screens and with
those obtained in a duct without screens. Results in the time domain are obtained
by applying an inverse Fourier transform to the frequency results.
Keywords: dual-BEM, thin body, sound absorption.
1 Introduction
The demand for quieter environments has led to the imposition of lower noise
levels inside buildings. Those limits are usually imposed by legislation and
building codes. Sound pressure levels inside buildings are often reduced by
installing sound attenuation systems in ventilation ducts.
Keywords
dual-BEM, thin body, sound absorption.
Related Book
Other papers in this volume
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