Experimental investigation into Lagrangian statistics of droplets in homogeneous isotropic turbulence

TL;DR

This study experimentally explores how finite-sized, neutrally buoyant droplets behave in turbulent flows, revealing size-dependent Lagrangian dynamics and providing insights into droplet-turbulence interactions.

Contribution

It provides new experimental data on the Lagrangian statistics of finite-sized droplets, highlighting size effects on their dynamic behavior in turbulence.

Findings

Larger droplets have longer velocity integral times.

Droplets show extended ballistic regimes with increasing size.

Droplets behave similarly to rigid particles in turbulence.

Abstract

We experimentally investigate the Lagrangian dynamics of finite-sized, neutrally buoyant droplets in homogeneous isotropic turbulence. The droplet size follows a log-normal distribution whose average value decreases with increasing Reynolds number, reflecting enhanced turbulent breakup. While size-conditioned velocity and acceleration statistics show only weak finite-size dependence, temporal measures reveal clear size-dependent dynamics: larger droplets exhibit longer Lagrangian velocity integral times and an extended ballistic regime in their mean squared displacement. These findings indicate that though droplets exhibit mild deformation and internal circulation, they behave similarly to finite-size rigid particles in terms of Lagrangian dynamics. Our study opens the way to study droplet-laden turbulence and droplet-flow interactions.