Lagrangian particle simulation of tracer dispersion in the lee of a schematic two-dimensional hill

Spray, a 3D Lagrangian particle model for the simulation of complex flow dispersion, is presented. Based on the measured values of the first two moments of the turbulent flow velocity, the mean fields are computed over a regular grid using a mass-consistent model, whereas the turbulence structure is simply interpolated. From these fields, trajectories of tracer particles are computed using a linear formulation of the Langevin equation, with a correlated, skewed forcing. The computed concentration field turns out to be in good agreement with the observed one. In detail, ground-level profiles and vertical cross sections of concentration are compared, showing the important effects resulting from the topographic influence on the flow structure. -from Authors