Dispersion of traffic exhausts in urban street canyons with tree plantings - Experimental and numerical investigations

Wind tunnel experiments and numerical computations have been performed in order to investigate the influence of avenue-like tree plantings on the dispersion of traffic exhaust in an urban street canyon. Reduced natural ventilation and enhanced pollutant concentrations have been found in the pres-ence of trees. A comparison of experimental and numerical results shows qualitative good, but quantitative rather poor agreement. In the numerical computations, flow velocities are underestimated and pollutant concentrations are overestimated.