Comparisons of a Lagrangian particle model for urban dispersion with laboratory experiments

Dispersion in urban environment is simulated by a Lagrangian particle model with uncoupled equations for vertical and horizontal dispersion. The acceleration term is derived according to the well-mixed condition. The model is compared with laboratory experiments conducted for short and tall model urban canopies. The approximations involved by using uncoupled equations and by neglecting the momentum fluxes are assessed. The effect of the appropriate scaling variables determining the Lagrangian time and length scales are also discussed.