Three-dimensional finite difference-time domain simulation of moving sound sources: point source arrays and circular sources

Abstract This paper describes the theoretical analysis of moving sound sources and their implementation in the three-dimensional finite difference-time domain (FDTD) method. The theoretical directivities of a moving point source array and a circular source are derived. Numerical experiments were conducted for point source arrays and circular sources in the three-dimensional sound field for various source configurations. It was confirmed that the FDTD method can calculate with an error of less than 1% for frequencies up to 1 kHz and Mach numbers up to 0.3 for a grid spacing of 13 mm. It was found that the Doppler effect causes high-frequency characteristics of directivity to appear in the moving direction and low-frequency characteristics to appear in the opposite direction. The proposed method is effective for analyzing both moving point source arrays and circular sources.