[1] Yoshiki Kuramoto, "Chemical Oscillations, Waves, and Turbulence" (Dover, New York, 2003).

Coupled limit-cycle system is reduced coupled phase oscillator system by the phase reduction, and as a representative model the Kuramoto model has extensively studied.

weak coupling ← → strong coupling

In the Kuramoto model, the oscillators evolve according to the equations:

The oscillators have the natural frequencies, which are often assumed to obey the Lorentz distribution:

The above figures show that the system undergoes the synchronization trainsition when the coupling strength K is increased. That is, with small K the oscillators move incoherently while with strong coupling they cooperate and tend to have similar phases.