Abstract Summary (Max 250 words)
Particle settling and transport in slurries significantly affect the efficiency and energy consumption of slurry-based operations in industries such as energy, mineral processing, and wastewater treatment. In many industrial slurries, the carrier fluid exhibits a finite yield stress, yet the conditions under which particle wake structure changes with increasing inertia in these fluids remain incompletely characterized. In this study, direct numerical simulations are performed to investigate the gravity-driven settling dynamics of one and two spherical particles in Newtonian and Bingham fluids using the lattice-Boltzmann method coupled with an immersed boundary approach in a fully periodic domain. The numerical framework is first validated for Newtonian fluids against established numerical benchmark data over a broad range of particle Reynolds numbers, from creeping flow (Re < 1) to transitional regimes (200 < Re < 2000). The approach is then extended to Bingham fluids to capture yield stress effects over Bingham numbers of 0.8 to 8. These predictions are compared against the available numerical and experimental data. This work demonstrates that the yield surface fundamentally modifies particle wake structure and drag behavior and alters the wake transitions relative to Newtonian settling. These findings provide mechanistic insight for developing predictive models of particle-laden yield stress flows.
