Ammonia (NH3) emission rates (ER) of ten commercial layer houses (six high-rise or HR houses and four manure-belt or MB houses) with different manure handling or dietary schemes were monitored for one year in Iowa (IA) and Pennsylvania (PA). Gaseous (NH3 and CO2) concentrations of incoming and exhaust air streams were measured using custom-designed portable monitoring units that shared similar performance to EPA-approved measurement apparatus. Building ventilation rates were determined by calibrated CO2 mass balance using the latest metabolic rate data for modern laying hens. The field monitoring involved a total of 386 and 164 house-day measurements or 18,528 and 7,872 30-min emission data points for the HR houses and the MB houses, respectively. The ER showed considerable diurnal and seasonal variations. The annual mean ERs (g NH3 hen-1 d-1) and standard errors were 0.90 ±0.027 for IA-HR houses with standard diet, 0.81 ±0.02 for IA-HR houses with a nutritionally balanced 1% lower crude protein diet, 0.83 ±0.070 for PA-HR houses with standard diet, 0.054 ±0.0035 for IAMB houses with daily manure removal, and 0.094 ±0.006 for PA-MB houses with twice a week manure removal. Mass balance of nitrogen (N) intake and output performed for IA-HR houses revealed a total N intake recovery of 94% to 101%, further verifying the certainty of the NH3 ER measurements. Results of the study contribute to the U.S. national inventory on NH3 emissions from animal feeding operations, particularly laying hen facilities as affected by housing type, manure handling scheme, crude protein content of the diet, and geographical location.

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Separated flow past a hump in a turbulent boundary layer is studied numerically using detached-eddy simulation (DES), zonal detached-eddy simulation (ZDES), delayed detached-eddy simulation (DDES), and Reynolds-averaged Navier–Stokes (RANS) modeling. The geometry is smooth so the separation point is a function of the flow solution. Comparisons to experimental data show that RANS with the Spalart–Allmaras turbulence model predicts the mean-field statistics well. The ZDES and DDES methods perform better than the DES formulation and are comparable to RANS in most statistics. Analyses motivate that modeled-stress depletion near the separation point contributes to differences observed in the DES variants. The order of accuracy of the flow solver ACUSOLVE is also documented.

Modeling high Reynolds number (Re) flow is important for understanding wind loading on structures, transport and dispersion of airborne contaminants, and turbulence patterns in urban areas. This study reports a high fidelity computational fluid dynamics simulation of flow about a surface mounted cube for a Reynolds number sufficiently high to represent atmospheric flow conditions. Results from detached eddy simulations (DES) and zonal DES that compare well with field experiment data are presented. A study of reducing grid resolution indicates that further grid refinement would not make a significant difference in the flow field, adding confidence in the accuracy of the results. We additionally consider what features are captured by coarser grids. The conclusion is that these methods can produce high fidelity simulations of high Reynolds number atmospheric flow conditions with a modest grid resolution.

<p class="MsoNormal" style="text-align: left; margin: 0cm 0cm 0pt; layout-grid-mode: char;" align="left"><span class="text"><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;">The release of a harmful contaminant into a densely populated area could quickly affect significant numbers of people. The results of a physical modeling study of the atmospheric transport and dispersion of a hypothetical chlorine release are presented as a case study for situational awareness and preparedness planning. Both a Computational Fluid Dynamics (CFD) model and a rapid response model are used to illustrate different modeling aspects in an effort to aid development of emergency response preparedness for a worst-case scenario event. The accuracy of the two approaches and an analysis of the maximum possible impact of the release on the nearby population are assessed. The two models are compared and contrasted with a primary difference resulting from the ensemble average approach of the rapid response model versus the specific realization produced by the CFD model.</span></span><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;"></span></p>