Investigation of permeability of superquadric granular materials based on discrete element-lattice Boltzmann method

Accurate characterization of the permeability of granular materials is fundamental in geotechnical and geological engineering, as it governs fluid transport processes that directly influence soil stability, groundwater flow, and the safety of structures. While the influence of porosity on permeability is well recognized, the role of particle shape remains insufficiently quantified due to the complexity of particle-level interactions and flow behavior in disordered packings. In this study, we present a numerical framework that integrates the discrete element-lattice Boltzmann method to investigate the permeability characteristics of granular systems composed of non-spherical particles. Particles are modeled using superquadric equations, allowing systematic control over shape parameters such as aspect ratio and blockiness, while ensuring volume consistency across cases. The contact geometry between adjacent particles is resolved using Newton's iteration to accurately compute overlaps and normal vectors. Granular materials with varying porosities are generated using DEM, and the resulting pore-scale fluid flow is simulated using LBM to capture detailed transport phenomena. The porosity, blockiness, and aspect ratio parameters are individually varied to isolate their effects on average flow velocity, dimensionless permeability, flow anisotropy, and tortuosity. Results show that porosity has a strong positive correlation with flow efficiency, but the aspect ratio of the particles exerts an even more pronounced influence. Specifically, permeability and flow velocity reach a maximum when the particle aspect ratio equals one, indicating that geometric symmetry enhances pore connectivity and reduces flow resistance. Deviations from this balanced geometry, either through elongation or flattening, lead to increased surface-fluid interaction and reduced permeability. In contrast, the blockiness parameter shows minimal impact across all evaluated metrics. These results highlight that particle geometry influences permeability and point to practical strategies for improving and tailoring granular materials in both engineering design and environmental management.