Hydro-micromechanical modeling of wave propagation in saturated granular crystals

Hongyang Cheng*, Stefan Luding, Nicolás Rivas, Jens Harting, Vanessa Magnanimo

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    1 Citation (Scopus)
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    Abstract

    Biot theory predicts wave velocities in a saturated granular medium using the pore geometry, viscosity, densities, and elastic moduli of the solid skeleton and pore fluid, neglecting the interaction between constituent particles and local flow, which becomes essential as the wavelength decreases. Here, a hydro-micromechanical model, for direct numerical simulations of wave propagation in saturated granular media, is implemented by two-way coupling the lattice Boltzmann method (LBM) and the discrete element method (DEM), which resolve the pore-scale hydrodynamics and intergranular behavior, respectively. The coupling scheme is benchmarked with the terminal velocity of a single sphere settling in a fluid. In order to mimic a small amplitude pressure wave entering a saturated granular medium, an oscillating pressure boundary on the fluid is implemented and benchmarked with the one-dimensional wave equation. The effects of input waveforms and frequencies on the dispersion relations in 3D saturated poroelastic media are investigated with granular face-centered-cubic crystals. Finally, the pressure and shear wave velocities predicted by the numerical model at various effective confining pressures are found to be in excellent agreement with Biot analytical solutions, including his prediction for slow compressional waves.

    Original languageEnglish
    Pages (from-to)1115-1139
    Number of pages25
    JournalInternational journal for numerical and analytical methods in geomechanics
    Volume43
    Issue number5
    Early online date19 Mar 2019
    DOIs
    Publication statusPublished - 10 Apr 2019

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    Keywords

    • acoustic source
    • Biot theory
    • discrete element method
    • fluid-solid coupling
    • lattice Boltzmann method
    • wave propagation

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