Lagrangian dispersion in coastal applications.

The role played by the turbulent mixing in the Lagrangian dispersion of tracers in a tidally-driven, mid-latitude, shallow-water environment is here discussed. The Eulerian carrying flow is supplied by a turbulent oscillating boundary layer without and with rotation. In the purely oscillating case, the dispersion of the particulate is stronger in the near-wall region and the diffusivity along the main flow direction is larger than the other ones. For the value of Rossby number herein considered, rotation strongly affects particle dispersion and increases the mixing efficiency of particles within the whole fluid column, up to the near surface region. Diffusion along the spanwise direction is comparable to that in the streamwise one, and consequently the time needed to completely homogenize the physical properties associated to the particulate is reduced.