Modeling toxic gas dispersion over urban area using GIS and CFD

Abstract

To simulate toxic gas dispersion over urban area with consideration of the influence of wind, buildings and other obstacles within the dispersion site, an integrated strategy incorporating computational fluid dynamics (CFD) and GIS technologies is investigated. CFD is able to couple wind field with pollutant dispersion process and provide realistic simulation for geometrically complex scenarios, however, inadequate of geometry construction for urban scale applications. This paper focuses on how to take advantage of the available GIS data, the visualization and spatial discretization capabilities of GIS in CFD modeling. Topography and building data stored in GIS database are used to extract the detailed coordinates and heights of the buildings around the area of interest. Furthermore, a methodology of domain discretization, with restrict to underneath geometrical boundary, is proposed to construct computational grids for CFD simulations. For illustration purposes, a mixed residential and commercial area of Lujiazui in Shanghai is investigated. The CFD software, CFX5.5, is employed to predict plume concentrations, and the output can be rendered dynamically in GIS environment.