A Sustainable and Particles Dispersion in the Wake of Motor Vehicule

Nanoparticles released from tailpipes of ground vehicles are a major contributor to air quality worsening. As it is question of small sized solid particles, they can cause important damages, particularly to human health. The dynamics of these ultrafine particles (UFP) is strongly related to the characteristics of the airflow. The present work focused on a numerical study of a two-phase flow developing in the wake of a simplified vehicle (square back Ahmed body). The goal is to get a better understanding of the dynamics of these UFP in order to prevent their infiltration in a following vehicle. Two cases are analyzed corresponding to two different upstream velocities [endif]-->. A URANS model coupled with a tracking Lagrangian particle approach was used to predict the two-phase flow. Results show a decrease of the UFP concentration with the distance to the emission point. In addition, the concentration profiles show a highly dissymmetrical shape in the near wake recirculation region, which can be explained by the off-centered position of the exhaust pipe and the impact of the large coherent structures. The particles concentration profiles tend to homogenize. Furthermore, dispersion increases with the distance to the vehicle and its speed due to the dispersion process.