Modeling Turbulent Flow in Urban Areas

A turbulent flow model for urban areas, RUSTIC (Realistic Urban Spread and Transport of Intrusive Contaminants), is being developed as a simplified CFD model to be fast-running and user-friendly. RUSTIC is capable of utilizing terrain data in a variety of widely available data formats. Buildings can be added to the terrain data using either commercially available data or user defined buildings specified in a simple text file format. The model can be initialized with a variety of meteorological data inputs, ranging from a single wind measurement to a three-dimensional mesoscale forecast model grid. The user has several options available for selecting between speed and fidelity in running the model. Output from RUSTIC is used to drive a transport and dispersion model.

RUSTIC simulations are compared with measurements made during the Joint Urban 2003 experiment by sonic anemometers, both at ground level and on towers, as well as profiles from sodars located in the central business district (CBD). RUSTIC is shown to be capable of reproducing the main features of the flow in an urban CBD and providing realistic estimates of the turbulence generated by the buildings.