Periodic sedimentation in a Stokesian fluid

Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Sep;74(3 Pt 2):035302. doi: 10.1103/PhysRevE.74.035302. Epub 2006 Sep 8.

Abstract

We study the sedimentation of two identical but nonspherical particles sedimenting in a Stokesian fluid. Experiments and numerical simulations reveal periodic orbits wherein the bodies mutually induce an in-phase rotational motion accompanied by periodic modulations of sedimentation speed and separation distance. We term these "tumbling orbits" and find that they appear over a broad range of body shapes.