Modeling micromechanics of solid-fluid interactions in granular media
Stone, Tonya W.
Peters, John F.
Embargo TypeVisible to MSU only for 2 Years
Embargo Lift Date2021-12-15
Micromechanics of solid-fluid interactions can play a key role controlling macro-scale engineering behavior of granular media. The main objective of this study is to numerically investigate the micromechanics involved in solid-fluid mixtures to develop a better understanding of the macroscopic behavior of granular media for different applications. This is accomplished by developing a numerical model coupling the Discrete Element Method (DEM) and the Lattice Boltzmann Method (LBM) and employing it to study three distinct yet interrelated applications throughout the course of this research. In the first application, the DEM model is used to provide a clear relationship between energy dissipated by micro-scale mechanisms versus the traditional engineering definition based on macro-scale (continuum) parameters to develop a better understanding for the frictional behavior of granular media. Macroscopic frictional behavior of granular materials is of great importance for studying several complex problems such as fault slip and landslides. In the second application, the DEM-LBM model is employed for studying the undrained condition of dense granular media. While the majority of previous modeling approaches did not realistically represent non-uniform strain conditions that exist in geomechanical problems, including the LBM in the proposed model offers a realistic approach to simulate the undrained condition since the fluid can locally conserve the system volume. For the third application, the DEM-LBM model is used to study discontinuous shear thickening in a dense solid-fluid suspension. Shear thickening in a fluid occurs when the viscosity of the fluid increases with increasing applied strain rate. The DEM-LBM results for discontinuous shear thickening were compared to experimental data and proved to be an accurate approach at reproducing this phenomenon. The validated DEM-LBM model is then used to develop a physics-based constitutive model for discontinuous shear thickening-shear thinning in granular media-fluid suspension. A closed-form model is then calibrated using the DEM-LBM model and validated against existing experimental test results reported in the literature. Findings of this research demonstrate how micromechanical modeling can be employed to address challenging problems in granular media involving solid-fluid interaction.