Many-particle dispersion in anisotropic magnetohydrodynamic turbulence

Magnetohydrodynamic (MHD) turbulence is an essential aspect of a wide range of astrophysical systems, among them convection in stellar interiors, mixing of material from accretion disks into stars, and the explosive dynamics in stellar atmospheres that drive stellar winds. MHD turbulence differs structurally from hydrodynamic turbulence. For example, in hydrodynamic turbulence small-scale vorticity tends to be organized in the form of vortex filaments, but in MHD turbulence vortex sheets form. We investigate the structure of MHD turbulence from the Lagrangian viewpoint based on the trajectories of many Lagrangian tracer particles. We evaluate standard Lagrangian statistics such as single-particle diffusion curves and velocity autocorrelation functions. We also demonstrate that the convex hull of a group of dense Lagrangian tracer particles can provide new information about anisotropic dispersion, derived from the surface area and volume of a cluster of particles.