Abstract
Keywords: Numerical Simulations, Urban Street Canyons, Traffic Pollution, and Turbulent Dispersion
We report on numerical simulations of turbulent flows over simplified (laboratory size) and realistic urban street canyons with dispersion of the passive pollutants. Several extensions of the standard two-equation (k-) eddy-viscosity turbulence model have been investigated. These extensions and modifications are expected to remove some of several well-known deficiencies of the standard model that are relevant for accurate simulations of environmental flows. Here considered effects are: the surface roughness, the generalised treatment of the wall-function approach, redefined productions of the turbulent kinetic energy (so called Kato-Launder model and linearised production by Guimet and Laurence) and the Durbin's time-scale limiter. In addition to these modelling aspects, we addressed also numerical issues associated with simple, numerically efficient and robust representations of the blocked flow regions (passive elements approach). Then, a series of numerical simulations are performed including simplified 2D and 3D urban street canyons at laboratory scales and the full-scale geometry of a traffic pollution in the Goettinger street in Hanover, Germany. For all simulated situations, good agreement with available laboratory and field measurements are obtained demonstrating promising potentials for future applications