Sedimentation of Four or Six Spheres in a Newtonian Fluid at Low Reynolds Numbers

The Demonstration simulates the sedimentation of four or six spheres with a particular initial symmetric geometric arrangement. A Newtonian fluid at low Reynolds numbers is assumed.

The data on the positions of the spheres versus time comes from a three-dimensional numerical simulation using a method called Stokesian dynamics, which was developed in the mid-1980s by Bossis and Brady. It is apparent from the simulation that, as time elapses, the spheres return periodically to their initial geometrical arrangement.