Nonequilibrium continuous transition in rotating turbulence

We study the saturation of three-dimensional unstable perturbations on a fast rotating

turbulent flow using direct numerical simulations (DNSs). We observe a transition from states

dominated by coherent two-dimensional modes to states with three-dimensional variations (quasi-

2D behavior), as the global rotation is varied, under the effect of Kolmogorov forcing. We find this

transition akin to a critical phenomenon, wherein the order parameter scales with the distance to

the critical point raised to an exponent. The exponent itself deviates from the predicted mean

field value. Also, the nature of the fluctuations of the order parameter near the critical point

indicates the presence of an on-off intermittency. The critical rotation rate at which the transition

occurs exhibits a linear scaling behaviour with the forcing wave number. Linear stability analysis

is used to verify the instability mechanisms and to find the linear threshold estimates; we find

these to be in good agreement with the 3D nonlinear DNS results.