Spoiling air pollution dispersion: A numerical investigation of exhaust plume dispersion from cars with rear spoilers

This paper conducts an investigation into the influence of a rear spoiler on the dispersion of a car’s exhaust plume. Computational fluid dynamics modelling is employed to examine the relationship between concentrations of air pollutants downstream of a moving vehicle and the location/orientation of its rear spoiler. Changes in the down-force, drag, downstream mean exhaust plume concentration and the mean air quality concentration for nearby pedestrians/cyclists are estimated for differing vehicle speeds. The results show that certain rear spoiler configurations produced an increase in mean head-height concentration of over 40% while others reduce the concentration of up to 18%. The rear spoiler angle of attack is found to have a large influence on head-height concentrations in the vehicular wake.

Research highlights
► We examined effects of vehicle rear spoiler on dispersion of exhaust emissions.
► 5 different rear spoiler configurations were examined.
► Some configurations produced an increase in mean head-height concentration up to 57%.
► Other configurations produced reductions in this concentration of up to 18%.
► Angle of attack was found to have a large effect on concentrations in vehicular wake.
► Results show rear spoilers can be designed to minimise environmental impacts.