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Translation of transient acoustic fields
1Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, United Kingdom.
Abstract:
A method is presented for the translation of acoustic field data from a source to a target region. Field data are represented as spherical harmonic expansions on spheres surrounding the source and target regions, respectively, and expansions are translated using a "point and shoot" method using the Kirchhoff-Helmholtz integral to carry out an axial translation from one sphere to the other. The principal motivation for the method is its use in a time-domain fast multipole method, and test cases reflective of this application are presented. The method converges to six digits for appropriate values of parameters, and for the values of N considered here, computational effort scales approximately as N2, where N is the order of spherical harmonic expansion for the field data. The method is causal and thus avoids artifacts generated in methods that are not based on intrinsically causal formulations.
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