| | 1 | '''Large eddy simulation of flow and pollutant dispersion in street canyons''' \\ |
| | 2 | Responsible: Martina Krane \\ |
| | 3 | Project type: Diplomarbeit (equivalent to master thesis) \\ |
| | 4 | Duration: 11/12/2006 - 10/12/2007 \\\\ |
| | 5 | The objective of the project is the examination of turbulent wind flow and pollutant dispersion in street canyons. A street canyon is a narrow street flanked by tall buildings. The street canyon domain is a region where large amounts of pollutants are released near the ground from motor vehicle exhausts and near the roof level from domestic (or industrial) chimneys. The analysis and forecasting of a single source contribution to the total pollution does require a fairly precise knowledge of the dispersion process inside the street canyon. The flow inside a street canyon is characterized by manifold recirculation regions overlapping with complex wake structures and the fluid motion governing the dispersion process is highly turbulent. To understand the flow and dispersion characteristics inside street canyons a lot of studies have already been made. |
| | 6 | An often used model to analyse flow and pollutant dispersion in street canyons is the k- ε model, which parametrizes the turbulence of the flow completely. \\ |
| | 7 | Sini et al. (1996: Pollutant dispersion and thermal effects in urban street canyons; Atmos. Env. Vol. 30, No. 15, 2659-2677) have shown that for wind directions approximately perpendicular to the street canyon three different flow regimes depending on the value of the aspect ratio (street width/ canyon height) are formed, the isolated roughness flow, the wake interference flow and the skimming flow. The number and arrangement of the vortex inside the street canyon affect the vertical exchange and so the pollutant dispersion inside the street canyon significantly. Aim of this project is to use the LES-model PALM, which resolves the turbulence of the flow, to analyse if Sini et al. describe the vortex inside the street canyon correctly and if the turbulence parametrization in k- ε models can describe the turbulent exchange in street canyons quantitatively and qualitatively correct. Besides this the flow pattern and the pollutant dispersion inside street canyons shall be examined for three different aspect ratios. |
