Single-particle transport in spherical and non-spherical particle-packed porous media

Fine particle transport in porous media governs contaminant migration and the internal stability of geotechnical structures. While skeleton particle morphology significantly affects transport mechanisms, investigations comparing these processes in spherical and non-spherical particle-packed porous media remain limited. This study used the discrete element method coupled with lattice Boltzmann method and planar laser-induced fluorescence experiments, to investigate single-particle transport under different hydraulic gradients (i = 0.000 17–0.0017) and size ratios (dn/D = 0.133–0.4). Results revealed that compared with spherical particle-packed media (SPM), non-spherical particle-packed porous media (NSPM) exhibit higher porosity and superior pore connectivity, more complex pore networks and more tortuous high-velocity flow channels. Particle transport trajectory complexity in NSPM is greater than that in SPM, exhibiting stronger transverse dispersion, greater velocity fluctuations, and random directional changes. The passage probability is 3.4%–7.8% greater for fine particles in NSPM than in SPM under varying dn/D at constant i and 3.3%–7.0% greater under varying i at constant dn/D; however, longer and more variable transport times, while increasing hydraulic gradient, can increase the passage probability and reduce the transport time. The particle transport trajectory tortuosity in NSPM is greater than that in SPM. At a constant i of 0.000 85, as dn/D increased from 0.133 to 0.4, the average tortuosity increased from 1.22 to 1.33 in SPM and from 1.53 to 1.59 in NSPM. At a constant dn/D of 0.267, as i increased from 0.000 17 to 0.0017, the average tortuosity increased from 1.20 to 1.40 in SPM and from 1.42 to 1.72 in NSPM.