Adjoint-based monopole synthesis of sound sources with complex directivities

Numerical time domain methods are continuously improving and gain in importance in virtual acoustics. The accurate modeling of directive sound sources is a prerequisite for acoustical simulations. In contrast to frequency domain methods, the directivity pattern of sound sources cannot be analytically implemented in the time domain directly. The sound sources are rather approximated by the superposition of monopoles around the directive sound source. For that purpose, an adjoint-based monopole synthesis method is discretized in a finite differences time domain (FDTD) scheme. Therein, the full non-linear Euler equations are solved by means of computational aeroacoustics (CAA). To efficiently compute reference sound fields, an analytical complex directivity point source (CDPS) model is embedded into the existing architecture of the CAA solver, which enables a decomposition of the computing domain to parallelize the computation. In order to avoid unfavorable interferences between the monopoles in FDTD, its spatial expansion is analyzed. Finally, the adjoint-based monopole synthesis method is considered for a dipole, a quadrupole and a (complex) circular piston model. The results are evaluated by graphical representations and technical measures, e.g., 3D directivity pattern figures. The analysis is not only limited to the reproduction of the reference directivity patterns, as it is as well the intention of this thesis to examine the procedure of the adjoint-based monopole synthesis method.

Author dc:creator

• Hölter, Arne Birk

Licence dc:rights.uri

• https://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

en

Identifier URI

http://dx.doi.org/10.14279/depositonce-15891

OAI identifier oai:identifier

oai:depositonce.tu-berlin.de:11303/17112