DescriptionBiot's theory predicts wave velocities in a saturated granular medium using the properties of the solid skeleton and pore fluid, but neglects the interaction between constituent particles and local squirt flow, which becomes essential as the wavelength decreases. In this work, we explore the missing ingredients in Biot's macroscopic description of wave propagation, by mean of particle-based numerical simulations. The lattice Boltzmann method (LBM) and the discrete element method (DEM), which resolve the pore-scale hydrodynamics and intergranular behavior, respectively, are two-way coupled to simulate wave propagation in saturated granular packings.
After comparing existing the two existing coupling schemes, we apply isotropic compression on a fully-saturated packing of polydisperse, frictional spheres to study the influence of the pore fluid on the acoustic behavior. An oscillating pressure boundary is used to emit acoustic waves from the fluid boundary.
The dispersion relations of the saturated granular packings are obtained from coupled LBM-DEM simulations, while DEM simulations provide the dispersion relations of the corresponding dry solid skeleton, as well as its long-wavelength elastic moduli. Using these as input, the wave velocities in the saturated system are computed with Biot's theory and compared with the numerical results from the LBM-DEM simulations.
|21 Jul 2019 → 26 Jul 2019
|8th International Conference on Discrete Element Methods, DEM 2019
|Degree of Recognition