Sedimentation characteristics of two side-by-side elliptical particles in two-dimensional framework

The free sedimentation of non-spherical particles is widely encountered in engineering applications such as deep-sea mining. In this study, the sedimentation behavior of two side-by-side elliptical particles in a two-dimensional confined channel is investigated using computational fluid dynamics simulations. Particular attention is paid to the effects of channel width L* and initial particle spacing d* on inter-particle interactions and settling dynamics. The particle motion is characterized through the analysis of centroid trajectories, velocity time series, phase-space evolution, and flow field structures. Within the investigated (L*,d*) parameter range, the observed sedimentation behaviors are classified into three representative regimes: periodic oscillatory settling, damped settling toward equilibrium, and steady vertical settling. A regime map is constructed to delineate the transitions among these behaviors. The results suggest that, under the present two-dimensional laminar-flow conditions, the channel width plays the dominant role in determining the sedimentation regime, whereas the initial particle spacing mainly affects the number, timing, and intensity of inter-particle interaction events.