Nonuniversal transition to condensate formation in two-dimensional turbulence

TL;DR

This paper investigates how the transition to condensate formation in two-dimensional turbulence varies with different forcing mechanisms, revealing nonuniversal behavior and characterizing critical phenomena.

Contribution

It demonstrates that the transition to condensate formation is nonuniversal, depending on the forcing type, and quantifies the effects of large-scale friction on critical parameters.

Findings

Supercritical transition with constant energy input forcing.

Subcritical transition with bistability and hysteresis under linear instability forcing.

Large-scale friction influences critical exponents and transition points.

Abstract

The occurrence of system-scale coherent structures, so-called condensates, is a well-known phenomenon in two-dimensional turbulence. Here, the transition to condensate formation is investigated as a function of the magnitude of the force and for different types of forcing. Random forces with constant mean energy input lead to a supercritical transition, while forcing through a small-scale linear instability results in a subcritical transition with bistability and hysteresis. That is, the transition to condensate formation in two-dimensional turbulence is nonuniversal. For the supercritical case we quantify the effect of large-scale friction on the value of the critical exponent and the location of the critical point.