Dance in a turbulent ball

Slice from a 3D two-way coupled DNS homogeneous isotropic turbulent flow containing 35 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 0.2, mass loading 0.5 and total time 1.1s.