Nonequilibrium continuous transition in a fast rotating turbulence

¹ Department of Physics, Indian Institute of Technology Kharagpur - Kharagpur, 721 302, India
² Department of Applied Mechanics & Biomedical Engineering, Indian Institute of Technology Madras Chennai, 600036, India

Received: 4 January 2025
Accepted: 21 February 2025

Abstract

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.