Finite element model analysis of scattering by objects in complex seafloor environments

Abstract

Underwater object detection and classification efforts are complicated by object burial within complex seafloor interfaces, which can alter the acoustic scattering signature in a variety of ways based on the level of object burial, orientation, frequency, grazing angle, and the variation of the seafloor topography. In this investigation, three-dimensional finite element models of acoustic scattering from objects in seafloor sediment were developed, to explore the effects that interface bathymetry and roughness have on the acoustic scattering, and to capture these effects within the model. Models were developed for comparison with measured acoustic scattering data from objects in real in situ ocean environments. Far-field scattering results outside the model domain were achievable through a numerical Green's function determination process. A high fidelity model that can account for the effects of interface rippling and mounding, small-scale roughness, and target/environment asymmetry has great appeal for detection and classification efforts. [Work supported by the Office of Naval Research and by the Strategic Environmental Research and Development Program.]