New Target-Strength Computation Modules for the Ray-Trace Model ARTES (Nya Moduler foer Beraekning av Malstyrka foer Stralgangsmodellen ARTES).

摘要

ARTES (Acoustic Ray tracing Target Echo Strength) is a ray-trace model for evaluation of active sonar target echoes, including environmental effects. The Kirchoff approximation is utilized within its target-echo module to compute the scattered field. In the present report, three new target modules for ARTES are developed: (1) a 2D finite-difference (FD) module. This module allows accurate modeling of the scattering from complex target geometries. In principle, it can easily be extended to 3D, but computer limitations make 3D computations too demanding at the moment. (2) A 2D Fourier module for cylindrically symmetric targets. The target may be composed of fluid as well as solid shells. The computations are fast, but one is restricted to the symmetric target shapes. (3) A 3D Fourier module for spherically symmetric targets. The load on the computer does not increase for 3D computations for the Fourier method. Several examples are given, with excellent agreement between the FD and Fourier methods for examples where both methods can be used.