有限要素音場解析へのKrylov部分空間法の適用 : 反復解法を利用した大規模音場数値解析 その2

Abstract

Krylov subspace iterative solvers are applied to large-scale finite element sound field analyses of architectural rooms. First, convergence behaviors are compared among four iterative solvers. Results show that Conjugate Orthogonal Conjugate Gradient (COCG) method offers the best characteristics for finite-element (FE) analysis from the viewpoint of robustness of convergence and computation time. Then, two investigations to reduce computation time of the COCG method were carried out. Results show the following. (1) The averaged residual of sound pressure levels between COCG method and direct method are less than 0.1dB if the convergence criterion is set to 10^<-4> and the maximum residual of those between COCG method and direct method is less than 0.2dB if the convergence criterion is set to 10^<-6>. (2) The computation time of the COCG method with diagonal preconditioning is about 30% shorter than that of COCG method without preconditioning. Finally, sound pressure level distributions obtained using the authors' FEM are compared with those obtained by fast multipole BEM (FMBEM) and measurements.