CLUSTERS OF PARTICLES FALLING IN A VISCOUS FLUID WITH PERIODIC BOUNDARY CONDITIONS

M. L.  Ekiel-Jeżewska and B. U. Felderhof
Phys. Fluids 18, 121502 (2006)




Three identical point particles falling under gravity in a viscous fluid with periodic boundary conditions. Stable (top) and unstable (down) solutions of the equations of Stokesian dynamics are shown for two initial configurations: horizontal equilateral triangles with side lengths d=0.42 and d=0.43 close to a  critical size d=0.4242. Four periodic cubic cells of unit length are visible in each window. The frame of reference is moving with the time-averaged velocity of the red and blue particles.


T43_front_long

Transition from periodic to irregular motion, caused by an extremely small numerical perturbation
(d=0.43, front view).


See also: M. L.  Ekiel-Jeżewska and B. U. Felderhof, Periodic sedimentation of three particles in periodic boundary conditions,  Phys. Fluids 17, 093102 (2005).    PDF