Valutazione di distribuzioni in un problema di dispersione turbolenta

Enviromental control problems demand an increasing care in modelling diffusion in real turbulent flows. In this paper we will deal with a problem arising with the so-called "Lagrangian" or "random flight" models of dispersion. In such models some statistical informations about flow turbulence (mean value, variance and possibly skewness of the velocity component distributions) are used to compute the trajectories of a large number of marked fluid particles. The ensemble average of such trajectories allows an evaluation of the concentration of the marker. These dispersion models are specially appropriate for inhomogeneous turbulence fields, such as it occurs in the atmosphere over hills or near large buildings