  We present a theoretical and numerical study of Fourier space triad phase
dynamics in one-dimensional stochastically forced Burgers equation at Reynolds
number $\mathrm{Re} \approx 2.7 \times 10^4$. We demonstrate that Fourier triad
phases over the inertial range display a collective behaviour characterised by
intermittent periods of synchronisation and alignment, reminiscent of Kuramoto
model (Kuramoto 1984) and directly related to collisions of shocks in physical
space. These periods of synchronisation favour efficient energy fluxes across
the inertial range towards small scales, resulting in strong bursts of
dissipation and enhanced coherence of Fourier energy spectrum. The fast time
scale of the onset of synchronisation relegates energy dynamics to a passive
role: this is further examined using a reduced system with the Fourier
amplitudes fixed in time -- a phase-only model. We show that intermittent triad
phase dynamics persists without amplitude evolution and we broadly recover many
of the characteristics of the full Burgers system. In addition, for both full
Burgers and phase-only systems the physical space velocity statistics reveals
that triad phase alignment is directly related to the non-Gaussian statistics
typically associated with structure-function intermittency in turbulent
systems.
