Regular arrays of driven colloidal particles synchronised into steady collective dynamical states by their hydrodynamic coupling interactions. The shaded circles show the particles’ positions at the initial, 20th and 40th frames of a video recording. The particles in the three-particle system perform in-phase oscillations, the ones in the four-particle system perform oscillations in anti-phase with their neighbours, and the particles in the five-particle system feature phase locking between neighbours. The frame rate is between 200 and 300 frames per second, depending on the case.
Reproduced by permission from Damet et al., Soft Matter 8, 8672–8. Copyright (2012) The Royal Society of Chemistry.
Fig. 17.1 — Hydrodynamic synchronisation of colloids