Gunderson Aaron M, Isakson Marcia J, Bonomo Anthony L
Applied Research Laboratories, The University of Texas at Austin, Austin, Texas 78758, USA.
J Acoust Soc Am. 2019 Sep;146(3):2093. doi: 10.1121/1.5125250.
A method is presented for numerically determining Green's functions for the purpose of calculating the far-field scattering from objects resting on or buried within the seafloor. To obtain the far-field scattering, initial evaluation of the three-dimensional near-field solution is required, through finite element analysis or other means. The Green's function and its spatial derivatives are then numerically evaluated for input into the Helmholtz-Kirchhoff integral, yielding the far-field scattering solution. This numerical technique determines the Green's function directly and avoids requiring analytic forms of Green's functions, which may be difficult or time consuming to evaluate for complex environments. This paper demonstrates the effectiveness of applying the numerical Green's function determination technique in conjunction with near-field results from finite element models to determine the far-field scattering for various elastic targets in free-field and flat seafloor environments. The method may be generalizable to arbitrary targets at complicated interfaces, incorporating interface roughness, layering, and volume inhomogeneities.
本文提出了一种数值确定格林函数的方法，用于计算位于海底或埋于海底的物体的远场散射。为了获得远场散射，需要通过有限元分析或其他方法对三维近场解进行初始评估。然后对格林函数及其空间导数进行数值评估，以输入到亥姆霍兹 - 基尔霍夫积分中，从而得到远场散射解。这种数值技术直接确定格林函数，避免了需要格林函数的解析形式，对于复杂环境而言，解析形式的评估可能困难或耗时。本文展示了将数值格林函数确定技术与有限元模型的近场结果相结合，以确定自由场和平坦海底环境中各种弹性目标的远场散射的有效性。该方法可推广到具有界面粗糙度、分层和体积不均匀性的复杂界面处的任意目标。
