Intermittency of velocity time increments in turbulence

TL;DR

This paper investigates the statistical properties of turbulent velocity fluctuations in different observational frameworks, revealing distinct intermittency characteristics between Lagrangian and Eulerian measurements in turbulence.

Contribution

It provides a comparative analysis of velocity fluctuation statistics in Lagrangian, static, and Eulerian turbulence cases, highlighting differences in intermittency and flow dynamics.

Findings

Lagrangian velocity fluctuations show unique intermittency signatures.

Static and virtual probe cases share properties with Eulerian velocity statistics.

Dynamic Lagrangian case reflects the global flow dynamics.

Abstract

We analyze the statistics of turbulent velocity fluctuations in the time domain. Three cases are computed numerically and compared: (i) the time traces of Lagrangian fluid particles in a (3D) turbulent flow (referred to as the "dynamic" case); (ii) the time evolution of tracers advected by a frozen turbulent field (the "static" case), and (iii) the evolution in time of the velocity recorded at a fixed location in an evolving Eulerian velocity field, as it would be measured by a local probe (referred to as the "virtual probe" case). We observe that the static case and the virtual probe cases share many properties with Eulerian velocity statistics. The dynamic (Lagrangian) case is clearly different; it bears the signature of the global dynamics of the flow.