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The motivation for this work stems from the increased number of high-rise buildings/skyscrapers all over the world, and in London, UK, and hence the necessity to see their effect on the local environment. We concentrate on the mean velocities, Reynolds stresses, turbulent kinetic energies (TKEs) and tracer concentrations. We look at their variations with height at two main locations within the building area, and downstream the buildings. The pollution source is placed at the top of the central building, representing an emission from a Combined Heat and Power (CHP) plant. We see how a tall building may have a positive effect at the lower levels, but a negative one at the higher levels in terms of pollution levels. Mean velocities at the higher levels (over 60 m in real life) are reduced at both locations (within the building area and downstream it), whilst Reynolds stresses and TKEs increase. However, despite the observed enhanced turbulence at the higher levels, mean concentrations increase, indicating that the mean flow has a greater influence on the dispersion. At the lower levels (Z < 60 m), the presence of a tall building enhanced dispersion (hence lower concentrations) for many of the configurations.

This study evaluated road shape and roadside barrier impact on near-road air pollution dispersion using FLUENT computational fluid dynamics (CFD) model. Simulated road shapes are three types, namely at-grade, depressed, and filled road. The realizable k-ε model in FLUENT CFD code was used to simulate the flow and dispersion around road. The selected concentration profile results were compared with the wind tunnel experiments. The overall concentration profile results show good agreement with the wind tunnel results. The results showed that noise barriers, which positioned around the at-grade road, decrease the horizontal impact distance (In this study, the impact distance was defined as the distance from road surface origin coordinate to the position whose mass fraction is 0.1.) lower 0.33~0.65 times and change the vertical air pollution impact distance larger 2.0~2.27 times than those of no barrier case. In case of filled road, noise barriers decrease the horizontal impact distance lower 0.24~0.65 times and change the vertical air pollution impact distance larger 3.33~3.55 times than those of no barrier case. The depressed road increase 1.53~1.68 times the vertical air pollution impact distance. It contributes the decrease of horizontal air pollution impact distance 0.32~0.60 times compare with no barrier case.