Time Domain Boundary Element Methods for Acoustic Scattering
Doktorsavhandling, 2008

In room acoustics, numerical computation of scattering phenomena is an important subject, since it is needed to accurately predict the influence of reflectors, the audience, balconies, etc, on the perceived acoustic quality of auditoria. The large physical volumes of auditoria and the wide frequency content of music and speech, together with the complicated geometries involved however, makes predictions in room acoustics a challenging task from a computational point of view. In Paper A, an exact analytical method for computing scattering phenomena in simple situations, the boss-model, is compared with measurements. Paper B presents a semi-analytical method, the time domain boundary element method, which may be used to extend the boss model in Paper A to arbitrary geometries. In the thesis, connections between the two papers are established by comparing the two methods through numerical implementations. The appendices contain details and starting points for extensions of the theory. The time domain boundary element method is implemented using Hermite field interpolation in space and time, while the boundary is discretized using curved triangles, which in turn are defined by interpolating quadric surfaces associated with each node. With this approach, both field and geometry are continuous across boundary elements and time intervals. Moreover, hyper- and strongly singular integrals that appear in the regularization process required for numerical implementation are calculated using vector potentials. In Paper A it is shown that the boss model agrees well with measurements. Initial implementations of the theory of time domain boundary element models in Paper B moreover show promising correlations with analytical benchmark solutions.

hypersingular

time domain

room acoustics

acoustic scattering

regularization

vector potential

transient

curved surface

boundary element method

boss model

Hermite interpolation

Sal VH, Sven Hultins Gata 6, Chalmers Tekniska Högskola, Göteborg
Opponent: Prof. Dr.-Ing. Martin Ochmann, Department of Mathematics, Physics and Chemistry, TFH Berlin - University of Applied Sciences, Germany

Författare

Georgios Natsiopoulos

Chalmers, Bygg- och miljöteknik, Teknisk akustik, Rumsakustik

Evaluation of a boss model and subtraction technique for predicting wideband scattering phenomena in room acoustics

Journal of the Acoustical Society of America,; Vol. 119(2006)p. 2798-2803

Artikel i vetenskaplig tidskrift

Ämneskategorier

Strömningsmekanik och akustik

ISBN

978-91-7385-116-9

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 2797

Sal VH, Sven Hultins Gata 6, Chalmers Tekniska Högskola, Göteborg

Opponent: Prof. Dr.-Ing. Martin Ochmann, Department of Mathematics, Physics and Chemistry, TFH Berlin - University of Applied Sciences, Germany