Sedimentation of elliptical particles in Bingham fluids using graphics processing unit accelerated immersed boundary-lattice Boltzmann method

Abstract

Elliptical particles settling in Bingham fluids in a confined, the vertical channel is studied using the immersed boundary-lattice Boltzmann method to understand their sedimentation characteristics. The present elliptical particles-Bingham fluids two-phase systems involve a single particle, a pair of particles, a chain of particles, and a cluster of particles. The graphics processing unit (GPU) is used to improve computational efficiency. Special attention is placed on the influence of yield stress on sedimentation behavior. For a pair of elliptic particles, alongside the drafting-kissing-tumbling (DKT) mode or non-DKT sedimentation mode, a periodic sedimentation mode is found. The results indicate that two elliptic particles keep a kissing state and their trajectories and orientations periodically change during settling in the confined channel. For the elliptic particles chain, the first kissing occurs between the middle and lower particles regarding any Bingham number. Moreover, particles form the cluster for different inclination angles of the particle chain at the Bingham number Bn = 0.02. For the cluster of particles (15 × 15), the effect of vortex interaction around particles in Newtonian fluids is revealed, and the rheological property of the fluid-particle interaction in Bingham fluids is displayed. Overall, the role of yield stress on the sedimentation of elliptic particles is significant. With the acceleration of GPU, the present method has great potential for modeling large numbers of particles settling in non-Newtonian fluids.