Numerical modelling of transient dispersion of air pollution in perpendicular urban street intersection with detail inclusion of traffic dynamics

In this study, the authors focus on the utilisation of computer modelling for the detailed identification of transient pollutants' dispersion in a perpendicular intersection equipped with traffic lights. Passenger cars are considered as the main source of the air pollution in the intersection. Car movement is at the same time a major driving force affecting the air flow in the crossroad area. A model based on an Eulerian-Lagrangian approach to moving objects has been integrated into a commercial CFD software package StarCD. The inclusion of traffic dynamics is used for a correct description of dispersion processes. The air pollution concentration fields were obtained from numerical predictions for traffic light switching periods of 60, 90, and 120 s. The correctness of the developed dispersion model was assessed on the base of NOx concentration measurements carried out in a real city intersection with similar geometry as in the numerical model.