Investigation on settling behavior of single cuboid-like particle in a quiescent fluid

The settling behavior of non-spherical particles in quiescent water stands as one of the most common natural phenomena. This study investigates the impact of different initial orientations on settling behavior of non-sphere particle. The Reynolds number Re ranges from 10 to 400. Two particle sizes (dn), three liquid viscosities (v) and three modes are conducted to control the Re range and initial orientations. Using particle image velocimetry (PIV), both the trajectory and flow field are captured, while the Smoothed Particle Hydrodynamics (SPH) method with modified dynamic boundary conditions reveals the process of pressure change. The results clarify the influence of different orientations on settling behavior elements (velocity, trajectory, angle, etc.) and their interrelationships. The mechanism causing trajectory variations among the three orientations is attributed to distinct positions of flow separation points. Furthermore, the analysis includes an exploration of vortex shedding characteristics and its hydrodynamic effects. Vortex shedding can strengthen the negative hydrodynamic pressure but it increases by no >10% and has negligible impact on the trajectory. These findings contribute to a deeper understanding of intricate phenomena, such as particle group settling processes and sediment transport.