Dispersion of Air Pollution & Penetration into the Local Environment

Numerical & Analytical Modelling

Computational Modelling of Urban Pollution Dispersion
University of Cambridge

Cambridge is undertaking computational simulations relevant to the DAPPLE field campaigns using a suite of models of different complexity. Further information can be obtained via the heading link.

Development of an urban canopy model
University of Reading

At Reading University an urban canopy model is being developed which includes a physically accurate representation of the coupling between street-scale circulations and the boundary layer above. The main dynamical effect of the buildings is to act as a distributed drag force which causes the flow to decelerate. The layout of buildings is usually random and the effects of individual buildings are smeared out. Hence an urban area can be represented by a horizontally averaged canopy of resistance. The characteristic drag force can be obtained from considering the layout and form of the buildings. Urban areas have been represented by an effective roughness length in the past - the advantage in using a canopy approach is that the vertical structure of wind and turbulence is resolved by the model.

Computational Fluid Dynamics
Imperial College London

In addition to the DAPPLE fieldwork and wind tunnel experiments, an extensive CFD work is being carried out at Imperial College using the time-dependent, mesh adaptive finite/spectral element code FLUIDITY. The Large Eddy Simulation (LES) capability of FLUIDITY in conjunction with the mesh-adaptivity is used for the simulations.

The main objective of the work is to use the detailed computational studies for assessing the spatial and temporal variability of pollutant concentrations at busy traffic intersections. These studies form a necessary and integral component of the overall personal exposure studies of the DAPPLE project and assist in their analysis and interpretation. Further details on the general features of FLUIDITY and work being carried out can be obtained via the heading link.