(513e) Sedimentation of Non-Spherical Particles, Using Smooth Particle Method

Sedimentation is a one of the processes which has been explored extensively both as a clarification technique and a typical case of the non-equilibrium dynamics. Most of the studies on the sedimentations are for spherical particles, where orientation of the particles does not matter, whereas this study focuses on the non-spherical rod like particles, embedded in a Newtonian fluid in the Stokes regime.

We used direct numerical simulations, using smooth profile (SPM) method to explore the sedimentation of the rigid rod like particles. These rod like particles are generated by joining the spherical particles, which enables us to use the SPM, without any extra effort. In SPM, particle surface smoothed out with a continuous function, whose value vary from 0 to 1, 0 represents fluid domain and 1 particle domain. We solved the Newton and Euler equations for the particles and fluid domain is obtained by solving a modified Navier Stokes equation, having a body force to enforce the rigidity of the particles. Direct inter-particle interactions are calculated using Weeks-Chandler-Andersen (WCA) type potential.

Preliminary analysis suggests that the average sedimentation velocity of the particles at low volume fraction is higher than the spherical particles, but with increasing volume fraction it becomes less than the spherical particles, mainly caused by the shift in orientation of the particles from vertical to the horizontal. Moreover, velocity fluctuations in both directions are higher than the spherical particles, caused by the long range hydrodynamic interactions.

The detailed analysis of the simulations is underway.