A FORMULATION OF THE FAST MULTIPOLE BOUNDARY ELEMENT METHOD (FMBEM) FOR ACOUSTIC RADIATION AND SCATTERING FROM THREE-DIMENSIONAL STRUCTURES

Compared to the traditional boundary element method (BEM), the single level fast multipole boundary element method (SLFMBEM) or the multipole boundary element method (MLFMBEM) reduces the computational complexity of a job from O(n(2)) to O(n(3/2)) or O(n log(2) n), respectively with n being the number of unknowns; this means a dramatical reduction in terms of CPU-time and storage requirement. Large scale problems, unsolvable with the traditional BEM, can be solved by using the FMBEM. In this paper the traditional BEM, SLFMBEM, and MLRMBEM are formulated within the framework of the Burton-Miller Collocation BEM for acoustic radiation and scattering from 3D structures. Attention is especially paid to the practical aspects of the method in order to get a reliable and efficient computation code. The performance of the method is tested with practical examples, including one for computing the head-related transfer function (HRTF) between 1000 and 18 000 Hz.