J2.2
Development and applications of CFD simulations in support of air quality studies involving buildings
Alan Huber, NOAA/ERL/ARL, Research Triangle Park, NC; and W. Tang, A. Flowe, B. Bell, K. Kuehlert, and W. Schwarz
There is a need to properly develop the application of Computational Fluid Dynamics (CFD) methods in support of air quality studies involving pollution sources near buildings at industrial sites. CFD models are emerging as a promising technology for such assessments, in part due to the advancing power of computational hardware and software. CFD simulations have the potential to yield more accurate solutions than other methodologies because it is a solution of the fundamental physics equations and includes the effects of detailed three-dimensional geometry and local environmental conditions. However, the tools are not well validated for environmental modeling and best-practice methodologies have not been established. Fluent, Inc and the US EPA National Exposure Research Laboratory are working cooperatively to help make CFD a proven and applied tool in support of environmental assessment studies.
The results of CFD simulations can both be directly used to better understand specific case studies as well as be used to support the development of better-simplified algorithms that may be generally applied. Unlike most currently used regulatory air quality models, CFD simulations are able to include specific details of building structures as well as a range of defined atmospheric turbulent boundary layers. Plume dispersion in absence of buildings are demonstrated to be comparable with standard plume dispersion models for point and line source pollutant emissions. Boundary layer turbulence is being simulated as characterized by surface roughness (characterized by u*) and surface heat flux (characterized by Monin-Obukhov length L).
This paper discusses ongoing development and application of CFD simulations through case studies using CFD software for simulating air pollutant concentrations from sources near buildings. Comparisons of CFD simulations to reference wind tunnel data and field measurement studies are presented to provide model performance evaluation/validation. An example comparison of the vertical wind component are shown in the following figure for flow over an array of 2-dimensional block buildings. This is one of several evaluation studies that will be presented. In addition to model evaluation/validation there is a need to identify the most efficient set-up for CFD simulations characterized by selection of grid size, turbulence models and other critical operational parameters. A report on progress for developing best practice methods for CFD applications in support of air quality studies involving buildings is presented.
Disclaimer - Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy
Figure. Example comparison of CFD results with wind tunnel data for vertical velocities.
Joint Session 2, Urban Scale Dispersion and Air Quality (Joint between the Fifth Symposium on the Urban Environment and the 13th Conference on the Applications of Air Pollution Meteorology with the A&WMA)
Wednesday, 25 August 2004, 9:00 AM-10:00 AM
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