A NUMERICAL STUDY OF 3-DIMENSIONAL JEFFERY ORBITS IN SHEAR-FLOW

We perform numerical simulations of rods and spheroids undergoing Jeff ery orbits in a variety of shear flows. The numerical simulations are based on the boundary element method, which allows for the accurate mo deling of the problem geometry. We compare the period of rotation for spheroids and rods, both far from walls and very close to walls. We fi nd that the wall effects in three dimensions are minimal, even for flo w in gaps not much larger than the longest dimension of the particle. We also show that two-dimensional simulations grossly overpredict the wall effects seen in three dimensions. Results are similar for both li near and nonlinear shear flows. We also briefly look at the orbital mo tion of a particle in close proximity to another particle, and show th at, again, there is very little effect on the period of rotation, alth ough the resulting centroid trajectories are very different from that of an isolated particle.