Single-particle trajectories in two-dimensional turbulence

We study two-dimensional turbulence from a Lagrangian point of view, by integrating the motion of an ensemble of passively advected particles in the velocity field provided by numerical simulations of forced Navier-Stokes equations in two space dimensions. The role of coherent structures is addressed and a summary of recent results on this problem is given. We discuss the statistical properties of single-particle trajectories in 2D turbulence and study their scaling and fractal behaviour. The preliminary results reported here indicate that particle paths in 2D turbulence seem to display a fractal nature characterized by a correlation dimension D2 ≈ 1.3. This value of the dimension is similar to that observed for drifter trajectories in ocean flows.