Experimental observation of 1/f noise in quasi-bidimensionnal turbulent flows

TL;DR

This paper reports the experimental detection of 1/f noise in quasi-2D turbulent flows, linking the noise to a renewal process driven by large-scale circulation polarity changes.

Contribution

It demonstrates the origin of 1/f noise in turbulence as a renewal process based on flow polarity states, a novel insight into turbulence dynamics.

Findings

1/f^{eta} noise observed with b1 b7 0.7 in flow spectra

The noise arises from a two-state renewal process of flow polarity

Statistical properties of polarity switching control the spectral exponent

Abstract

We report the experimental observation of $1/f^{\alpha}$ noise in quasi-bidimensionnal turbulence of an electromagnetically forced flow. The large scale velocity $U_L$ exhibits this power-law spectrum with $\alpha \simeq 0.7$ over a range of frequencies smaller than both the characteristic turn-over frequency and the damping rate of the flow. By studying the statistical properties of sojourn time in each polarity of $U_L$, we demonstrate that the $1/f^{\alpha}$ noise is generated by a renewal process, defined by a two-state model given by the polarities of the large scale circulation. The statistical properties of this renewal process are shown to control the value of the exponent $\alpha$.