Transient Turbulence in Taylor-Couette Flow

TL;DR

This paper provides the first direct observations of turbulence decay in Taylor-Couette flow, revealing that turbulence can be transient and its lifetime increases super-exponentially with Reynolds number, challenging the view of turbulence as an asymptotic state.

Contribution

It presents the first direct measurements of turbulent decay in Taylor-Couette flow and compares decay characteristics with other shear flows, suggesting turbulence may be inherently transient.

Findings

Turbulent states decay with lifetimes spanning five orders of magnitude.

Decay characteristics resemble those in other shear flows, including Poisson statistics.

Decay times increase super-exponentially with Reynolds number, remaining bounded.

Abstract

Recent studies have brought into question the view that at sufficiently high Reynolds number turbulence is an asymptotic state. We present the first direct observation of the decay of turbulent states in Taylor-Couette flow with lifetimes spanning five orders of magnitude. We also show that there is a regime where Taylor-Couette flow shares many of the decay characteristics observed in other shear flows, including Poisson statistics and the coexistence of laminar and turbulent patches. Our data suggest that characteristic decay times increase super-exponentially with increasing Reynolds number but remain bounded in agreement with the most recent data from pipe flow and with a recent theoretical model. This suggests that, contrary to the prevailing view, turbulence in linearly stable shear flows may be generically transient.