Sudden relaminarisation and lifetimes in forced isotropic turbulence

TL;DR

This paper reveals a surprising link between isotropic turbulence and wall-bounded shear flows, showing that turbulence can suddenly relaminarize with lifetimes increasing superexponentially as Reynolds number grows.

Contribution

It uncovers a connection between isotropic turbulence and wall-bounded shear flows, demonstrating similar phase-space dynamics and lifetime behaviors.

Findings

Sudden transitions from chaotic to simple flow states observed.

Survival probabilities of turbulence are exponential.

Turbulence lifetimes increase superexponentially with Reynolds number.

Abstract

We demonstrate an unexpected connection between isotropic turbulence and wall-bounded shear flows. We perform direct numerical simulations of isotropic turbulence forced at large scales at moderate Reynolds numbers and observe sudden transitions from a chaotic dynamics to a spatially simple flow, analogous to the laminar state in wall bounded shear flows. We find that the survival probabilities of turbulence are exponential and the typical lifetimes increase superexponentially with the Reynolds number. Our results suggest that both isotropic turbulence and wall-bounded shear flows qualitatively share the same phase-space dynamics.