Finite Difference Time Domain Simulation of Scattering From Submerged Elastic Bodies

Abstract

Abstract A two-dimensional finite difference time domain (FDTD) algorithm is implemented to simulate wave propagation and scattering in a heterogeneous fluid-elastic environment. The FDTD algorithm is fourth-order accurate in space and second-order accurate in time. The perfectly matched layer (PML) absorbing boundary condition is adapted to eliminate artificial reflections caused by the boundaries of the finite computational domain. Computational accuracy is verified by considering radiation from a periodic array of pulsed line sources and from a fluid line source near a submerged elastic layer. The finite difference results are in excellent agreement with the numerically evaluated spectral integrals which can be derived for these problems. The finite difference algorithm is then applied to scattering from a rough fluid-solid interface, and to scattering from an elastic cylinder above or buried beneath a rough fluid-solid interface. Scattered signals are processed with the Gaussian windowed transform, which provides an initial image representation for signature identification and classification algorithms.