# Lagrangian chaos and turbulent diffusivity

## TL;DR

This paper investigates how Lagrangian chaos influences passive scalar mixing in different fluid flow scenarios, comparing it with turbulence-induced mixing through experiments and theoretical models.

## Contribution

It introduces a comparative analysis of Lagrangian chaos effects on scalar mixing across various flow regimes using numerical, laboratory, and theoretical approaches.

## Key findings

- Lagrangian chaos enhances passive scalar mixing efficiency.
- Different flow configurations exhibit distinct mixing characteristics.
- Effective diffusivity and distributed chaos models effectively describe mixing processes.

## Abstract

Passive scalar mixing, produced by Lagrangian chaos generated a) by quasi-periodic (integrable) motion of three quasi-point vortices and b) by chaotic motion of three and six quasi-point vortices, has been studied and compared with turbulent mixing of passive scalar in 2D and 3D steady isotropic homogeneous turbulence and in turbulent wakes behind grid and behind cylinder. Results of numerical and laboratory experiments have been used and effective diffusivity approximation as well as distributed chaos approach have been applied to this problem.