Research Project 2
| EPA Grant Number: | R828771-0-01 |
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Title:
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Measurements and Large Eddy Simulations of Plume Dispersion in an Urban Boundary Layer |
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Investigators:
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Principal Investigator: Marc Parlange, Johns Hopkins University (JHU); Co-investigators: Charles Meneveau (JHU); Joseph Helble (University of Connecticut); John Ondov (University of Maryland) |
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Institutions |
Johns Hopkins University, Univ. of Connecticut, and Univ. of Maryland |
| Project Period: | October 1, 2001 to September 30, 2004 |
| Description: |
| The dispersion of aerosols from hazardous substance incinerators has long been a concern in urban environments. The transport of aerosols in this environment is extremely complex due to the spatial variability of surface heat fluxes and topography, land-water contrasts, drainage flows at night and mesoscale weather patterns. Large Eddy Simulation (LES) is becoming a reliable modern computational method to simulate turbulence in the atmospheric boundary layer (ABL) over complex terrain. We will expand the JHU - LES code to include Lagrangian calculations of atmospheric dispersion of particles released from the stack. We will also update the code to include the representation of structures (e.g. buildings) so that the turbulent flow and transport in the ABL over Baltimore will be more realistically simulated. Numerical simulations will employ new-generation sub-grid scale models that are particularly well suited to capture unresolved small-scale turbulence physics in complex environments in which turbulence deviates from the classical assumptions of isotropic inertial-range behavior. The new generation models can also deal effectively with the land-water contrast in the Baltimore harbor. The high-resolution LES will be conducted to identify the role of urban heterogeneity on regional atmospheric dynamics (i.e. wind fields and boundary layer height) as well as aerosol distributions with height. The JHU elastic lidar will be used in an a posteriori mode to assess the performance of the LES code to describe the aerosol particle distributions with height. Intensive field observations will be undertaken during January 2002, where the Lidar will be operated and micrometeorological measurements as well as in situ aerosol measurements at the stack and downstream will be taken by teams from the Universities of Connecticut and Maryland. Aerosol samples will be collected by deposition on a cascade impactor. Analysis of particle chemical composition on a particle-by-particle basis will be obtained by applying surface science methods including Auger spectroscopy, scanning electron microscopy, and energy dispersive x-ray analysis (SEM-EDAX), and x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The purpose of this project is to develop detailed understanding of the distribution functions associated with particulate matter emissions from incineration. These results will permit the development of more quantitative risk assessment for incinerator emissions, and can be used to design and implement control strategies for the most harmful fractions of the distribution. |
| Supplemental Keywords: |
| environmental engineering, air pollution, metal transport |