Long-range interactions and phase defects in chains of fluid-coupled   oscillators
  Eukaryotic cilia and flagella are chemo-mechanical oscillators capable of generating long-range coordinated motions known as metachronal waves. Pair synchronization is a fundamental requirement for these collective dynamics, but it is generally not sufficient for collective phase-locking, chiefly due to the effect of long-range interactions. Here we explore experimentally and numerically a minimal model for a ciliated surface; hydrodynamically coupled oscillators rotating above a no-slip plane. Increasing their distance from the wall profoundly effects the global dynamics, due to variations in hydrodynamic interaction range. The array undergoes a transition from a traveling wave to either a steady chevron pattern or one punctuated by periodic phase defects. Within the transition between these regimes the system displays behavior reminiscent of chimera states. 
Douglas R. Brumley, Nicolas Bruot, Jurij Kotar, Raymond E. Goldstein,   Pietro Cicuta, Marco Polin
physics.bio-ph cond-mat.soft math.DS physics.flu-dyn