An assessment of the effective density fluid model for backscattering from rough poroelastic interfaces

The effective density fluid model (EDFM) was developed to approximate the behavior of sediments governed by Biot’s theory of poroelasticity. Previously, it has been shown that the EDFM predicts reflection coefficients and backscattering strengths that are in close agreement with those of the full Biot model for the case of a homogeneous poroelastic half-space. However, it has not yet been determined to what extent the EDFM can be used in place of the full Biot model for other cases. In this work, the finite element method is used to compare the backscattering strengths predicted using the EDFM with the predictions of the full Biot model for three cases: a homogeneous poroelastic half-space with a rough interface, a poroelastic layer overlying an elastic half-space with both interfaces rough, and an inhomogeneous poroelastic half-space consisting of a shear modulus gradient with a rough interface. [Work supported by ONR, Ocean Acoustics.]