Soft Matter and Complex Systems Seminar

Dynamics of a cluster of non-Brownian particles falling under gravity in a viscous fluid at low-Reynolds-number regime has been extensively studied in the literature both for small and large number of particles and oscillating motions have been discovered. In this work, we investigate dynamics of clusters of many non-Brownian particles in regular configurations settling under gravity in a viscous fluid. The point particle approximation is applied for the hydrodynamic interactions. We find out that a wide range of regular initial configurations of many particles leads to very long lifetime of the cluster with periodic and quasi-periodic relative motion of particles. We vary the relative distance between the particles and observe how does it affect the dynamics. Several types of periodic and quasi-periodic solutions are discovered, or the system break up. For broad range of initial configurations we show that a slight change of initial conditions has a large influence on the system lifetime - we observe chaotic scattering.