Modelling Street-Scale Flow and Dispersion in Realistic Winds—Towards Coupling with Mesoscale Meteorological Models

Abstract

Further to our previous work—simulations of flow and dispersion in an oblique wind over the DAPPLE site (Xie and Castro, Atmos Environ 43:2174–2185, 2009)—large-eddy simulations of flows and dispersion over the same site in a wind perpendicular to Marylebone Road and the windward surfaces of most of the buildings were performed. The DAPPLE site is located at the intersection of Marylebone Road and Gloucester Place in central London. In order to investigate the effects of wind direction on flows and dispersion, the velocity and scalar fields in the perpendicular wind were compared with those in the oblique wind. Furthermore, realistic wind conditions measured on the BT Tower at 190 m above street level were processed and used to drive the numerical simulations of flows and dispersion at the DAPPLE site. This leads to significant predictive improvements of the dispersion compared with field measurements, which provides validation and confidence for coupling mesoscale meteorological models, e.g. the UK Met Office’s Unified Model and the NCAR’s Weather Research & Forecasting Model, with the street-scale large-eddy simulation of urban environments.