论文部分内容阅读
So far the boundary element method (BEM) has been widely used in solving acoustic problems, as it involves only surface discretization and solves infinite/semi-infinite problems naturally.Although the BEM reduces the problem dimensionality by one, the conventional method gives rise to dense and asymmetric coefficient matrices which result in large storage requirements and prohibitive analysis time.The computational complexity of the conventional method is O(N3) with direct solvers, or O(N2) with appropriate iterative solvers, and the storage requirements are O(N2), where N is the degree of freedom.This well-known drawback makes the BEM have difficulties with large models and be thus limited to numerical analyses of small bodies at low frequencies.To improve the efficiency, various fast approximation methods,such as the fast multipole method (FMM), the precorrected-FFT, the H-matrices and the adaptive cross approximation, have been proposed to accelerate the matrix-vector product in the BEM.Among them, the FMM seems to be one of the most widely accepted methods in the fast BEM community.Implemented with iterative solvers, the fast multipole BEM (FMBEM) reduces both the computational complexity and storage requirements to linear or quasilinear.