Air quality simulation of existing city block using chemistry-coupled CFD model

Abstract

In urban area, roadside air pollution is a serious environmental issue. In order to evaluate the roadside air pollution, it is requires to consider the both of chemical reaction and shape of buildings. In this study, a chemistry-coupled CFD (computational fluid dynamics) model was applied to assess the roadside air quality in a real situation. CBM-IV (Carbon bond mechanism IV) was used as the chemical reaction model coupled to the CFD model. The performance of the chemistry-coupled CFD model was tested in Umeda-shindo (Osaka prefecture), where roadside monitoring station is located, 24 hours on 23rd August 2010. The boundary conditions were calculated by air quality model WRF-CMAQ (Weather Research and Forecasting - Community Multiscale Air Quality Modeling System). Results showed that comparing with the observation data, the chemistry-coupled CFD results showed better accuracy in NOx concentration than the WRF-CMAQ data. In a real situation, the building geometry and mobile emission were found to have great impacts on the urban air quality in the CFD simulation, emphasizing the importance to assess the roadside air pollution with high spatial resolution.