Science Inventory

DEVELOPMENT AND APPLICATIONS OF CFD SIMULATIONS IN SUPPORT OF AIR QUALITY STUDIES INVOLVING BUILDINGS

Citation:

Huber, A. H., W Tang, A. Flowe, B. Bell, K. H. Kuehlert, AND W. Schwarz. DEVELOPMENT AND APPLICATIONS OF CFD SIMULATIONS IN SUPPORT OF AIR QUALITY STUDIES INVOLVING BUILDINGS. Presented at 13th Joint Conference on the Applications of Air Pollution Meteorology with the Air Waste Management Association, Vancouver, BC, Canada, August 23-27, 2004.

Impact/Purpose:

The goal of this research to develop models and computational tools to improve understanding of the functional relationships underlying human exposure to air toxics, and to reduce uncertainty in estimates of exposure to individuals and populations of concern. This goal will be met by addressing a number of key objectives in this task and include:

Model Research and Development: develop a multiroute/pathway/media human exposure and dose model for air toxics.

Model Application: apply model to an urban area (Houston, TX) to estimate human population exposure and dose.

Model Performance Evaluation: compare and evaluate exposure and dose estimates with independent model estimates or personal exposure measurements

Description:

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 they use a solution of the fundamental physics equations and include 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 more-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 the 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 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 is 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.

Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

Record Details:

Record Type:DOCUMENT( PRESENTATION/ PAPER)
Product Published Date:08/24/2004
Record Last Revised:06/21/2006
Record ID: 85276