| Abstract |
The gravity-driven sedimentation of particles in viscous fluids can be found in many applications. This problem has been studied for spherical or other well-defined shapes while the actual morphology of particles is ignored. However, it has been shown experimentally and numerically that the particle shape plays an important role in granular motion. This problem is generally described by the drafting-kissing-tumbling (DKT) phenomenon which is associated with the settling of particle pairs. In this paper, we numerically investigate the DKT process of irregular particles by coupling the mechanical and hydromechanical effects. Here, 16 irregular particles with different sphericity and roundness, including a spherical particle, are selected to study the effect of particle shape in the DKT process. Moreover, four orientations for each irregular particle are considered, which results in 65 sedimentation models. Our results show that particles with low sphericity are more sensitive to orientation because low sphericity particles tend to adjust the orientation and keep the broad side perpendicular to the fluid streamline direction. On the other hand, lower roundness accelerates the happening of the tumbling stage and makes the separation of particle pairs faster. Furthermore, the comparison of the vertical velocity shows that it decreases when roundness or sphericity is smaller. |
, Pejman Tahmasebi 
