A Comparative Study of Various Turbulence Models for Simulating Pollutant Dispersion within an Isolated Street Canyon

摘要

CFD calculations are carried out using the standard, RNG and realizable k-ε turbulence models to simulate the airflow and pollutant dispersion inside an isolated street canyon. The computed air velocity vector fields and pollutant concentration contours show that all the three studied k-ε models produce a very similar clockwise vortex structure that carries the pollutants released from the line source on the street floor towards the leeward side of the canyon. The calculated non-dimensional pollutant concentration distributions on both the leeward and windward walls of the canyon are compared with the wind tunnel measured data. It is revealed that (1) on the windward wall of the canyon, the calculated pollutant concentrations using the standard, RNG and realizable k-ε models are all in perfect agreement with the experimental observations, (2) the RNG and realizable k-ε models provide almost the same results for pollutant concentration distributions on the leeward wall of the canyon, (3) the RNG and realizable k-ε models overestimate greatly the pollutant concentration values on the leeward wall of the canyon, whereas the concentration distributions predicted by the standard k-ε model on the leeward wall are in reasonable agreement with the wind tunnel data.