Flow patterns in the sedimentation of an elliptical particle

We study the dynamics Ora single two-dimensional elliptical particle sedimenting in a Newtonian fluid using numerical simulations. The main emphasis in this work is to study the effect of boundaries on the flow patterns observed during sedimentation. The simulations were performed using it multi-block lattice Boltzmann method its well is a finite-element technique and the results are shown to be consistent. We have conducted it detailed study on the effects or density ratio, aspect ratio and the channel blockage ratio oil the flow patterns during sedimentation. As the channel blockage ratio is varied, our results show that there are five distinct modes of sedimentations oscillating, tumbling along the wall, vertical sedimentation, horizontal sedimetation and an inclined mode where the particle sediments with a non-trivial Orientation to the vertical. The inclined mode is shown to form it smooth bridge between the vertical and horizontal modes of sedimentation. For narrow channels. the mode of sedimentation Is found to be sensitively dependent on the Initial orientation of the particle. We present it phase diagram showing the transitions between the various modes of sedimentation with changing blockage ratio of the channel.MechanicsPhysics, Fluids & PlasmasSCI(E)EI25ARTICLE249-27262