  Local regions of anomalous particle dispersion, and intermittent events that
occur in turbulent flows can greatly influence the global statistical
description of the flow. These local behaviors can be identified and analyzed
by comparing the growth of neighboring convex hulls of Lagrangian tracer
particles. Although in our simulations of homogeneous turbulence the convex
hulls generally grow in size, after the Lagrangian particles that define the
convex hulls begin to disperse, our analysis reveals short periods when the
convex hulls of the Lagrangian particles shrink, evidence that particles are
not dispersing simply. Shrinkage can be associated with anisotropic flows,
since it occurs most frequently in the presence of a mean magnetic field or
thermal convection. We compare dispersion between a wide range of statistically
homogeneous and stationary turbulent flows ranging from homogeneous isotropic
Navier-Stokes turbulence over different configurations of magnetohydrodynamic
turbulence and Boussinesq convection.

Fluid Dynamics;Solar and Stellar Astrophysics;Plasma Physics