Two- and Three-Dimensional Simulation of Sound Attenuation by Cylinder Arrays

A finite-difference time-domain (FDTD) simulation coupled with an immersed-boundary method is used to investigate sound attenuation through both two-dimensional (2D) and three-dimensional (3D) cylinder arrays. The focus is on sound attenuation behaviors near Bragg's bandgap frequencies for periodic structures. Both 2D and 3D simulations show that the finite cylinder arrays produce significant sound attenuation near the bandgap frequencies, with more attenuation effects in the 2D cylinder arrays because of the uniformity of sound source and neglected structure diffraction in the third dimension. When extended to 3D simulation, which can accommodate physically realistic conditions, sound attenuation near Bragg's frequencies is reduced in comparison with 2D results. The 3D simulation also reaches a better agreement when comparing with the measurement data from the literature. Results and discussions on arrangement of cylinder arrays to achieve better sound attenuation effects are also presented.