Pore-Scale Modeling of Fine-Particle Migration in Granular Filters

Abstract

Fine-particle migration and associated internal erosion are major concerns for dam safety. Granular filters are used to prevent fine-particle migration, and several empirical models have been introduced for the design of these filters. Few computational techniques have tracked particle transport through the filters. This paper presents a three-dimensional transient fully coupled pore-scale model used to study the mechanism of fine-particle migration in granular filters. A pore-scale idealization of the fluid was achieved by using the lattice Boltzmann method, and the solid phase was modeled at a microscale using a discrete element method. The fluid forces applied on the particles were calculated on the basis of the momentum exchange between the fluid and particles. The proposed numerical technique was used to model the migration of base-soil particles through granular filters of different particle sizes. Results of conducted simulations provided the erosion percentages and flow rates during the simulations. The general behavior of the filters agreed with observations in laboratory experiments and with filter-design criteria reported in the literature. The proposed computational framework can be used effectively to model fine-particle migration at a pore scale with minimal assumptions, which would add a new dimension to filter-design problems.