Lagrangian dynamics and spatial distribution of particles in rotating turbulence

The dynamics of Lagrangian particles dispersed in rotating turbulence differ fundamentally from those observed in classical homogeneous isotropic turbulence (HIT). Rotation induces a pronounced two dimensionalisation of the carrier flow, governed by inertial waves and coherent columnar vortices, while particles experience additional Coriolis and centrifugal accelerations that compete with the standard Stokes drag. In this study, high-fidelity direct numerical simulations of HIT and rotating turbulence in a triply periodic domain are used to investigate the clustering and Lagrangian dynamics of millions of sub-Kolmogorov point particles. Increasing rotation reorganises both the flow and the dispersed phase: moderate rotation produces a domain-scale columnar vortex that expels inertial particles via drag-Coriolis coupling, while further increasing rotational effects amplifies centrifugal segregation and promotes anisotropic organisation, ultimately leading to the formation of slender, particle columns representative of a limiting clustering regime. Rotation significantly enhances particle clustering and anisotropy, shifting the maximum preferential concentration toward larger Stokes numbers. These trends are quantified using a new diagnostic based on the gyration tensor, which provides a unified description of cluster concentration, morphology and orientation across scales. To link these static signatures to their dynamical origin, the geometry and acceleration of Lagrangian trajectories are analysed. Increasing rotation suppresses vertical acceleration component while amplifying the planar one, steering particle dispersion toward an effectively two-dimensional regime. This transition is reflected in curvature and torsion statistics, which reveal more strongly bent trajectories and a reduced decorrelation from large-scale vortical structures.