Slice from a 3D two-way coupled DNS homogeneous isotropic turbulent flow containing 20 million solid particles. The background represents the Okubo-Weiss parameter, with particles avoiding red zones (vorticity overwhelms strain) and concentrating in the blue regions (the opposite). Taylor Reynolds is 35.4, Stokes 0.4 and mass loading 0.5.
Labyrinth with turbulent paths —Sergio Perez, Department of Aeronautics, Imperial College London

<p>Slice from a 3D two-way coupled DNS homogeneous isotropic turbulent flow containing 20 million solid particles. The background represents the Okubo-Weiss parameter, with particles avoiding red zones (vorticity overwhelms strain) and concentrating in the blue regions (the opposite). Taylor Reynolds is 35.4, Stokes 0.4 and mass loading 0.5.</p>

https://fluids.ac.uk/pictures/competition/10-labyrinth_with_turbulent_paths.png