A granular physics-based model for sediment dispersion

Abstract

Current models of dispersion in marine sediments include losses due to fluid viscosity and shearing at grain-grain contacts. An additional loss mechanism, which is well established in granular physics but is not included in existing models, is the inelasticity of normal compression at grain-grain contacts. Additionally, force-bearing contact networks, often called “force chains,” involve primarily normal compressive forces. These “force chains” are known to play a dominant role in force transmission in granular materials, including wave propagation. Using theoretical analysis of a 1D model “force chain” as well as DEM simulations in higher spatial dimension, we show that this granular mechanics perspective, where forces are transmitted along lossy force chains, may be able to explain salient features of the acoustic properties of marine sediments. In particular, the low and high-frequency behavior of the attenuation coefficient match a large collection of experimental data. [This was supported by the Office of Naval Research.]