Flow Patterns in the Sedimentation of an Elliptical Particle 

Xia, Z., Connington, K., Rapaka, S., Yue, P., Feng, J. J., & Chen, S.,

J. Fluid Mech. 625, 249-272 (2009)

Abstract - We study the dynamics of a single two-dimensional elliptical particle sedimenting in a channel in Newtonian fluid using numerical simulations. The simulations were performed using a multi-block lattice Boltzmann method as well as a finite element technique and the results are shown to be consistent. We have conducted a detailed study on the effects of density ratio, aspect ratio and the channel blockage ratio on the flow patterns during sedimentation. Our results show that there are five distinct modes of sedimentation: oscillating, tumbling along the wall, vertical sedimentation, horizontal sedimentation and an inclined mode where the particle sediments with a non-trivial orientation to the vertical. For narrow channels, the mode of sedimentation is found to be sensitively dependent on the initial orientation of the particle. We present a phase-diagram showing the transitions between the various modes of sedimentation with changing blockage ratio of the channel.