Micromechanical modeling of triphasic granular media

Area of Science:

• Geotechnical Engineering
• Environmental Engineering
• Computational Mechanics

Background:

• Understanding unsaturated granular media is crucial for various engineering applications.
• Existing models often struggle to capture complex pore-scale hydromechanical interactions.
• Accurate simulation of fluid flow and particle behavior is needed.

Purpose of the Study:

• To introduce the pore unit assembly-discrete element model (PUA-DEM) for simulating unsaturated granular media.
• To develop a framework that integrates pore-scale hydrodynamics with discrete element method (DEM).
• To enable accurate prediction of hydromechanical phenomena in partially saturated granular systems.

Main Methods:

• Developed a pore-scale hydromechanical framework (PUA-DEM) integrating DEM with pore-scale hydrodynamic models.
• Implemented a two-way coupling mechanism for bidirectional fluid-grain feedback.
• Utilized a dynamic pore-merging and retriangulation algorithm for computational efficiency.

Main Results:

• PUA-DEM accurately reproduced experimental data for glass beads and Ottawa sand.
• The model captured phenomena like capillary/viscous fingering and wetting-induced granular deformation.
• Numerical studies demonstrated the collective influence of capillary forces and saturation on granular response.

Conclusions:

• PUA-DEM effectively bridges pore- and particle-scale physics in unsaturated granular media.
• The framework offers transformative insights for geohazard mitigation, agriculture, and energy applications.
• Advances in predictive modeling of partially saturated granular systems are achieved.