Where do small, weakly inertial particles go in a turbulent flow?

TL;DR

This paper experimentally investigates how small, heavy particles behave in turbulent flows, revealing that increased inertia leads to preferential alignment and sampling of specific flow regions, affecting their trajectories.

Contribution

It provides new experimental evidence on the alignment and sampling behavior of inertial particles in turbulence, linking particle inertia to flow region preferences.

Findings

Increased particle inertia enhances alignment between velocity and acceleration differences.

Inertial particles preferentially sample strain-dominated regions.

Probability of collinearity between velocity and acceleration differences grows with density.

Abstract

We report experimental results on the dynamics of heavy particles of the size of the Kolmogorov-scale in a fully developed turbulent flow. The mixed Eulerian structure function of two-particle velocity and acceleration difference vectors <\delta v\cdot\delta a_p> was observed to increase significantly with particle inertia for identical flow conditions. We show that this increase is related to a preferential alignment between these dynamical quantities. With increasing particle density the probability for those two vectors to be collinear was observed to grow. We show that these results are consistent with the preferential sampling of strain-dominated regions by inertial particles.