Coherence of velocity fluctuations in turbulent flows

TL;DR

This paper studies how velocity fluctuations in turbulent flows remain correlated over space, revealing a universal exponential decay pattern that depends on flow characteristics, based on laboratory experiments.

Contribution

It demonstrates a universal exponential decay law for velocity fluctuation coherence in turbulent flows across different experimental setups.

Findings

Exponential decay of coherence with distance observed

Decay rate varies with flow properties

Universal behavior across different turbulent flows

Abstract

We investigate the spatio-temporal quantity of coherence for turbulent velocity fluctuations at spatial distances of the order or larger than the integral length scale $l_{0}$. Using controlled laboratory experiments, an exponential decay as a function of distance is observed with a decay rate which depends on the flow properties. The same law is observed in two different flows indicating that it can be a generic property of turbulent flows.