Interaction between two car models with application to pollutant dispersion

• Published in: Experimental thermal and fluid science 2023-05, Vol.143, p.110815, Article 110815
• Main Authors: Oussairan, Oumaïma, Varea, Emilien, Fokoua, Georges, Patte-Rouland, Béatrice, Murzyn, Frédéric
• Format: Article
• Language: English
• Subjects: Ahmed body; Dispersion; Engineering Sciences; LASER Doppler Velocimetry; Particle Number Concentration; Recirculation region; UltraFine Particles; Wake flow; Wind tunnel
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/j.expthermflusci.2022.110815

Nowadays, air quality monitoring is a major concern. Among pollutants, exhaust UltraFine Particles (UFP) have a harmful effect on health due to their small size and to their ability to penetrate the bloodstream, the respiratory system, the brain as well as the placental barrier. Out of the industrial emissions, road traffic is a major source of air pollution. UFP emitted from the cars can infiltrate the car cabin through leakages and ventilation system leading to poor air quality in the passenger compartment. Improving the knowledge regarding the dispersion of exhaust UFP in the wake of a car considering road traffic is then mandatory. In this paper, the dispersion of UFP is studied in the wake of a leading vehicle (LV) followed by a second one. Two rear slant angles (φ) for LV and 6 inter-vehicle distances are considered. Velocities and UFP concentrations are collected in a wind tunnel. The influence of the rear slant angle of the leading vehicle is discussed on both wake dynamics and concentration fields. The results indicate that a critical inter-vehicle distance can be identified above which the recirculation region remains unchanged. Considering the concentration fields, for a leading vehicle with φ=0°, the large recirculation region tends to entrap the particles and to homogenize the particle mixing. For φ=25°, the attachment of the flow in the rear slant angle has a strong impact on the particle dispersion. It leads to a small recirculation region, which entraps particles leading to a non-homogeneous mixing. The Particle Concentration fields in Number (PNC) reveal high levels in the exhaust tailpipe plane that can contribute to lower PNC levels in the car cabin. Comparisons with previous studies are discussed and possible recommendations are suggested. [Display omitted] •Flow characterization using 2D LDV measurements and Particle Number Concentration fields in the wake of Ahmed bodies having rear slant angles φ=0° and 25° were assessed.•Effects of a following vehicle on the wake flow topologies of Ahmed bodies were studied for 6 inter-vehicle distances.•Critical distance was revealed for each case above which, no major influence of the following vehicle was observed.•The volume and shape of the recirculation region play an important role in the mixing of particles.