Lagrangian one-particle velocity statistics in a turbulent flow

TL;DR

This paper analyzes Lagrangian velocity statistics in turbulent flow, estimating key constants, examining intermittency effects, and applying multifractal models to understand flow complexity.

Contribution

It provides new measurements of the Lagrangian Kolmogorov constant and quantifies intermittency effects using Extended Self-Similarity and multifractal analysis.

Findings

Lagrangian Kolmogorov constant affected by large-scale inhomogeneities

Velocity increment PDFs are highly non-Gaussian at small times

Deviations from Kolmogorov scaling are larger in Lagrangian than Eulerian frameworks

Abstract

We present Lagrangian one-particle statistics from the Risoe PTV experiment of a turbulent flow. We estimate the Lagrangian Kolmogorov constant $C_0$ and find that it is affected by the large scale inhomogeneities of the flow. The pdf of temporal velocity increments are highly non-Gaussian for small times which we interpret as a consequence of intermittency. Using Extended Self-Similarity we manage to quantify the intermittency and find that the deviations from Kolmogorov 1941 similarity scaling is larger in the Lagrangian framework than in the Eulerian. Through the multifractal model we calculate the multifractal dimension spectrum.