A comparison of the predictions of two competing sediment acoustic models for the scattering from inclusions in a sandy sediment

Abstract

Currently, there are several competing models that have been used to describe the acoustic properties of sandy sediments. These models include those that assume the sediment to behave as an acoustic fluid, a viscoelastic solid, and as a porous medium following Biot theory. Perhaps the two most sophisticated acoustic models that have been applied to sand are the Viscous Grain Shearing (VGS) model of Buckingham and the Extended Biot (EB) model of Chotiros. While both of these models have been used to fit measured sound speed dispersion and attenuation data, the reflection and scattering predictions made using these models differ. In this work, the finite element method is used to compare the scattered pressure predictions of these two models for the case of a sand half-space with a single inclusion. The geometry is assumed axisymmetric, and the inclusions are allowed to be either a fluid or an elastic solid. [Work supported by ONR, Ocean Acoustics.]