Hydrodynamic behavior of non-spherical particles in confined vertical flows: A resolved computational fluid dynamics-discrete element method study

We investigate the sedimentation and vertical hydraulic transport of non-spherical polymetallic nodules (PMNs) using the resolved computational fluid dynamics-discrete element method with multisphere particles spanning 98<Rep<2904. Shape effects induce 1.8–2.0 times drag enhancement relative to volume-equivalent spheres, arising from 50% larger frontal areas and wake asymmetry, reducing terminal velocities by 27%–29%. Vertical transport exhibits velocity-driven transitions from intermittent settling to stable convection, as demonstrated by residence time and drag force statistics. While PMNs exhibit enhanced rotational–translational coupling and broader force fluctuations, the regime progression qualitatively resembles that of volume-equivalent spherical particles. Drag variance evolution reveals contrasting behavior: small particles (d/D=0.082) show narrow distributions and wake suppression at higher velocities, while large particles (d/D=0.22) exhibit non-monotonic variance. These findings elucidate shape-confinement interactions in vertical transport and establish bounds on the applicability of volume-equivalent spherical particles in reduced-order models.