Numerical and Experimental Study of Wave Propagation in Water-Saturated Granular Media Using Effective Method Theories and a Full-Wave Numerical Simulation

Katsunori Mizuno,Yann Capdeville,Paul Cristini,Dimitri Komatitsch

doi:10.1109/joe.2020.2983865

Abstract

In this article, the detection of an object buried in marine sediments is investigated. Using the results from a series of experiments realized in a tank filled with water and calibrated glass beads, we evaluate the performances for a wide range of the value of the ratio kd of the grain size to the wavelength ( k is the wave number and d is the grain diameter) of three types of prediction tools. The first two prediction tools are based on the definition of an equivalent model. The first tool is based on the well-known Biot–Stoll theory (BM model) while the second tool uses nonperiodic homogenization to define effective velocity and anisotropy maps representing the medium (HM model). The last prediction tool implements a time-domain full-wave numerical method, which takes into account each grain separately (GM model). It is shown that a good agreement between experiments and numerical simulations can be achieved using the BM model for the low kd regime and the HM model for high kd regime.

Highlights

A COUSTIC systems with various operating frequencies are commonly used for the detection of objects buried in Manuscript received May 9, 2019; revised December 27, 2019 and March 17, 2020; accepted March 20, 2020
This grain size dependence makes the understanding of signals more difficult and engineers have to rely on an empirical method for the design of the new subbottom devices, which results in an increase in the total cost of the sea surveys
In the Grain Model (GM) simulation, we can see how the focusing of the emitted wave due to the concavity of the transducer is distorted by multiple scattering in the GM simulation

Summary

Introduction

A COUSTIC systems with various operating frequencies are commonly used for the detection of objects buried in Manuscript received May 9, 2019; revised December 27, 2019 and March 17, 2020; accepted March 20, 2020. This work was granted access to the HPC resources of Aix-Marseille Université financed by the project Equip@Meso (ANR-10EQPX-29-01) of the program “Investissements d’Avenir” supervised by the Agence Nationale de la Recherche under allocations b025. The propagation of acoustic waves in sediments is generally much more complicated than in water because sediments are in general granular media composed of solid and fluid parts. The acoustic characteristics, such as the sound speed and the attenuation, can dramatically change with the ratio of the grain size to the wavelength [7]–[11]. The availability of a good prediction tool of the reflected signals from buried objects in granular media is critical to facilitate the design of these systems

Methods

Results

Conclusion