Multi-Domain Boundary Element Method for Sound Fields in and around Porous Absorbers
Abstract:A multi-domain boundary element method for the calculation of sound fields in and around porous absorbers having a rigid frame is presented. Using the fact that the sound propagation in such absorbers can be described as if it would be an equivalent lossy fluid, the Kirchhoff-Helmholtz integral equation is applied. Consequently, an arbitrary configuration of porous absorbers and surrounding air space is treated as several acoustic domains with different wave numbers and impedances bounded together. A boundary element discretisation is applied to each of the domains. Afterwards, collocation leads to a system of linear equations. These equations may be solved to get both the sound pressure and its normal derivative at the boundaries. The method is implemented in 2D in a MATLAB code. The sound field generated by a plane wave incident on a cylinder of porous absorber material is used as a first benchmark. Results are compared to those of an analytical method using series of Hankel functions. The propagation of sound from a cylinder source above a finite depth absorber strip in a rigid baffle is calculated as a second example. Results of the method are compared to the results of a standard single domain boundary element method. The difference between the methods is discussed taking into account the extended and the local reaction of the absorber, respectively.
Document Type: Research Article
Publication date: 2003-01-01
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- Acta Acustica united with Acustica, published together with the European Acoustics Association (EAA), is an international, peer-reviewed journal on acoustics. It publishes original articles on all subjects in the field of acoustics, such as general linear acoustics, nonlinear acoustics, macrosonics, flow acoustics, atmospheric sound, underwater sound, ultrasonics, physical acoustics, structural acoustics, noise control, active control, environmental noise, building acoustics, room acoustics, acoustic materials, acoustic signal processing, computational and numerical acoustics, hearing, audiology and psychoacoustics, speech, musical acoustics, electroacoustics, auditory quality of systems. It reports on original scientific research in acoustics and on engineering applications. The journal considers scientific papers, technical and applied papers, book reviews, short communications, doctoral thesis abstracts, etc. In irregular intervals also special issues and review articles are published.
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