Numerical analysis of the dispersion characteristics of vehicular pollutants in exhaust plume under idle condition

The k-ε eddy dissipation model was used for the numerical simulation of the dispersing characteristics of vehicular exhaust plume under idle condition. The simulated results match very well with the experimental results. The effects of the initial emission concentration, exit velocity, exit direction and crosswind intensity were investigated parametrically. The initial pollutant concentration can increase the local concentrations but the pattern of dispersion remains the same. The exit velocity can increase the momentum of the jet, resulting in a deeper penetration downstream. The exit angle has stronger influence on pollutant dispersion than both initial pollutant concentration and exit velocity. Crosswind shows a significant effect on the dispersion of the exhaust plume also. It can divert the plume to disperse in the same direction of the wind with limited penetration in the downstream direction.