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Steve R. Diehl, Donald A. Burrows, Eric A. Hendricks, and Robert Keith

the size of the smallest building of interest. To initialize the grid and to supply the wind profile and turbulence energy and dissipation at the inflow boundary, a 1D numerical algorithm that contains the k – ω turbulence equations is included. The algorithm computes the flow as a function of altitude over a rough surface based on the sensible heat flux and surface roughness. RUSTIC can be run with an upwind heat flux that differs from the heat flux value around the larger buildings. 3. MESO

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Stevens T. Chan and Martin J. Leach

.S. Department of Homeland Security (DHS), we have recently developed a computational fluid dynamics (CFD) model for simulating airflow and dispersion of chemical/biological agents released in the urban environment. Our model, the Finite Element Model in 3-Dimensions and Massively Parallelized (FEM3MP), is based on solving the three-dimensional, time-dependent, incompressible Navier–Stokes equations on massively parallel computer platforms. The numerical algorithm is based on finite-element discretization

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Yansen Wang, Cheryl L. Klipp, Dennis M. Garvey, David A. Ligon, Chatt C. Williamson, Sam S. Chang, Rob K. Newsom, and Ronald Calhoun

north of the CBD for prevalent south and southwest wind directions. The profiler data were downloaded from the JU2003 data server maintained by personnel at the Dugway Proving Ground and were processed by colleagues at PNNL and ANL using the National Center for Atmospheric Research’s Improved Moment Algorithm ( De Wekker et al. 2004 ; Morse et al. 2002 ). Fairly persistent southwest wind conditions within a half hour ( Fig. 4 ; also see De Wekker et al. 2004 ; Lundquist and Mirocha 2006 ) during

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Cheryl Klipp

friction velocity. Bound.-Layer Meteor. , 93 , 197 – 209 . Wilczak , J. M. , S. P. Oncley , and S. A. Stage , 2001 : Sonic anemometer tilt correction algorithms. Bound.-Layer Meteor. , 99 , 127 – 150 . Fig . 1. Aerial photos of the five ARL tower sites, provided by courtesy of the U.S. Geological Survey. Towers 2 and 5 are in urban areas. Towers 1, 3, and 4 are in suburban areas. Scales differ among photos. Fig . 2. Daytime drag coefficient C D = u 2 * / U 2 as a function of wind

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Donald A. Burrows, Eric A. Hendricks, Steve R. Diehl, and Robert Keith

terms of footprints and heights. The algorithm reads the digital elevation model file, if present, and interpolates it into a 2D array. Complex buildings are created using overlapping footprints. To prevent lower building sections from overwriting the taller building sections, the footprints are sorted by rooftop height from lowest to highest. The building data are merged with the elevation array by adding the building height to the surface elevation for the cells that are inside of the footprint

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M. A. Nelson, E. R. Pardyjak, M. J. Brown, and J. C. Klewicki

do not have the calibration algorithms for each of the various makes and models of sonics used in this work. Van der Mollen et al. (2004) found the error in the flux measurements introduced by the lack of calibration to be dependent on the angle of attack and that it generally produced an underestimation of the flux magnitudes of between 5% and 15%. b. Spectral analyses Fluctuating velocity time series were calculated using a 30-min running-block average over the selected time period to remove

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Julia E. Flaherty, David Stock, and Brian Lamb

classical approach as The first term, with − C 1 as the leading coefficient, represents the return to isotropy. The second term, with − C 2 , was the rapid pressure strain, and the final two terms with C ′ 1 and C ′ 2 are the wall reflection terms. The final transport equation in the Reynolds stress model solves the dissipation rate with an expression similar to that of the k –ε model: The Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) pressure–velocity coupling algorithm was utilized

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M. A. Nelson, E. R. Pardyjak, J. C. Klewicki, S. U. Pol, and M. J. Brown

data presented here have not been corrected for these effects because the authors do not have the calibration algorithms for each of the various makes and models of sonics used in this work. Van der Mollen et al. (2004) found the error in the flux measurements introduced by the lack of calibration to be dependent on the angle of attack and that it generally produced an underestimation of the flux magnitudes between 5% and 15%. 4. Results and discussion a. Mean velocities Plan views of the

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