Numerical determination of Green's functions for far field scattering solutions

Typical finite element target scattering results are evaluated over a small physical domain and then propagated to the far field using the Helmholtz-Kirchhoff integral. This process allows for direct far field data-model comparison and is substantially faster than evaluation over a large domain. It does, however, require knowledge of the Green’s function of the target’s environment. For underwater buried targets, the two-medium Green’s function pertaining to the water and sediment is often not readily known and can be cumbersome to analytically solve or approximate, particularly when surface roughness or volume inhomogeneity is to be incorporated. Instead, the Green’s function can be determined directly through numerical methods. A direct process for numerical Green’s function determination in an arbitrary two-medium environment is proposed, and is used to determine the far field scattering from buried targets. Results are compared to experimental scattering records on buried elastic targets, and to other...