Experimental and Theoretical Investigations into Chimney Emissions

1975 ◽  
Vol 189 (1) ◽  
pp. 33-43 ◽  
Author(s):  
D. J. Moore
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Atmospheric Stability ◽  
Ground Level ◽  
Turbulent Velocity ◽  
Good Representation ◽  
Plume Dispersion ◽  
Ground Level Concentration ◽  
Simple Boundary ◽  
Theoretical Investigations

The simple ‘conical’ model of plume dispersion from an elevated source of effective height H (m) which indicates that the maximum ground-level concentration Cm (units m-3) is proportional to Q (rate of emission, units s-1) (σZ/ày)/ U (wind speed, ms-1) X H2 assumes that the vertical (σz) and cross-wind (σ y) spreads of plume material are similar functions of distance downwind For time average values of Cm of duration about 1 h, the length scale of the turbulence responsible for the cross-wind spread is, in general, much greater than that responsible for the vertical spread. This length *** l is restricted either by the depth h of the boundary layer or the height above the ground. In this case (σz /σy) in the expression for Cm must be replaced by (Some representative vertical turbulent velocity * l)/(Some representative cross-wind turbulent velocity X H) ’*** In conditions of strong thermal convection and light winds the turbulent vertical velocities are effectively independent of the wind speed and so the form of the first expression for Cm will change both with wind speed, atmospheric stability and the height of the plume in relation to the top of the boundary layer. Simple boundary-layer models for ‘convective’ and ‘windy’ conditions are shown to lead to equations for predicting Cm which are similar to those previously shown by the author to give a good representation of the ground-level concentrations in all categories of wind speed and stability observed on 2500 separate occasions in the Tilbury-Northfleet plume rise and dispersion experiment. The application of these expressions to other locations and sizes of plant is discussed.

scholarly journals Wind Turbulence Statistics of the Atmospheric Inertial Sublayer under Near-Neutral Conditions

Atmosphere ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1087
Author(s):  
Eslam Reda Lotfy ◽  
Zambri Harun
Keyword(s):  
Boundary Layer ◽  
Atmospheric Stability ◽  
Turbulent Velocity ◽  
Stability Conditions ◽  
Mean Velocity ◽  
Law Of The Wall ◽  
Turbulent Statistics ◽  
The Mean ◽  
The Law ◽  
Velocity Variances

The inertial sublayer comprises a considerable and critical portion of the turbulent atmospheric boundary layer. The mean windward velocity profile is described comprehensively by the Monin–Obukhov similarity theory, which is equivalent to the logarithmic law of the wall in the wind tunnel boundary layer. Similar logarithmic relations have been recently proposed to correlate turbulent velocity variances with height based on Townsend’s attached-eddy theory. The theory is particularly valid for high Reynolds-number flows, for example, atmospheric flow. However, the correlations have not been thoroughly examined, and a well-established model cannot be reached for all turbulent variances similar to the law of the wall of the mean-velocity. Moreover, the effect of atmospheric thermal condition on Townsend’s model has not been determined. In this research, we examined a dataset of free wind flow under a near-neutral range of atmospheric stability conditions. The results of the mean velocity reproduce the law of the wall with a slope of 2.45 and intercept of −13.5. The turbulent velocity variances were fitted by logarithmic profiles consistent with those in the literature. The windward and crosswind velocity variances obtained the average slopes of −1.3 and −1.7, respectively. The slopes and intercepts generally increased away from the neutral state. Meanwhile, the vertical velocity and temperature variances reached the ground-level values of 1.6 and 7.8, respectively, under the neutral condition. The authors expect this article to be a groundwork for a general model on the vertical profiles of turbulent statistics under all atmospheric stability conditions.

scholarly journals Maximum crosswind integrated ground level concentration in two stability classes

MAUSAM ◽  
2021 ◽  
Vol 64 (4) ◽  
pp. 655-662
Author(s):  
M.ABDEL WAHAB ◽  
KHALED SMESSA ◽  
M. EMBABY ◽  
SAWSAN EMELSAID
Keyword(s):  
Wind Speed ◽  
Laplace Transformation ◽  
Ground Level ◽  
Eddy Diffusivity ◽  
Concentration Data ◽  
Transformation Technique ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Ground Level Concentration ◽  
Vertical Height

bl 'kks/k i= esa fu"izHkkoh vkSj vfLFkj fLFkfr;ksa esa ØkWliou lekdfyr lkanz.k ysus ds fy, nks fn’kkvksa esa vfHkogu folj.k lehdj.k ¼ADE½ dks gy fd;k x;k gSA ykIykl :ikarj.k rduhd dk mi;ksx rFkk m/okZ/kj Å¡pkbZ ij vk/kkfjr iou xfr vkSj Hkaoj folj.k’khyrk dh leh{kk djrs gq, ;g gy fudkyk x;k gSA blds lkFk gh Hkw&Lrj  vkSj vf/kdre lkanz.kksa dk Hkh vkdyu fd;k x;k gSA geus bl ekWMy esa iwokZuqekfur vkSj izsf{kr lkanz.k vk¡dM+ksa ds e/; rqyuk djus ds fy, dksiugsxu ¼MsuekdZ½ ls fy, x, vkuqHkfod vk¡dM+ksa dk mi;ksx fd;k gSA  The advection diffusion equation (ADE) is solved in two directions to obtain the crosswind integrated concentration in neutral and unstable conditions. The solution is solved using Laplace transformation technique and considering the wind speed and eddy diffusivity depending on the vertical height. Also the ground level and maximum concentrations are estimated. We use in this model empirical data from Copenhagen (Denmark) to compare between predicted and observed concentration data.

scholarly journals An investigation of methods for injecting emissions from boreal wildfires using WRF-Chem during ARCTAS

2011 ◽  
Vol 11 (12) ◽  
pp. 5719-5744 ◽  
Author(s):  
W. R. Sessions ◽  
H. E. Fuelberg ◽  
R. A. Kahn ◽  
D. M. Winker
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Atmospheric Stability ◽  
Vertical Wind Shear ◽  
Ground Level ◽  
Naval Research ◽  
Plume Rise ◽  
Hotspot Detection ◽  
Transport Pathways ◽  
Thermal Buoyancy

Abstract. The Weather Research and Forecasting Model (WRF) is considered a "next generation" mesoscale meteorology model. The inclusion of a chemistry module (WRF-Chem) allows transport simulations of chemical and aerosol species such as those observed during NASA's Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) in 2008. The ARCTAS summer deployment phase during June and July coincided with large boreal wildfires in Saskatchewan and Eastern Russia. One of the most important aspects of simulating wildfire plume transport is the height at which emissions are injected. WRF-Chem contains an integrated one-dimensional plume rise model to determine the appropriate injection layer. The plume rise model accounts for thermal buoyancy associated with fires and local atmospheric stability. This paper describes a case study of a 10 day period during the Spring phase of ARCTAS. It compares results from the plume model against those of two more traditional injection methods: Injecting within the planetary boundary layer, and in a layer 3–5 km above ground level. Fire locations are satellite derived from the GOES Wildfire Automated Biomass Burning Algorithm (WF_ABBA) and the MODIS thermal hotspot detection. Two methods for preprocessing these fire data are compared: The prep_chem_sources method included with WRF-Chem, and the Naval Research Laboratory's Fire Locating and Monitoring of Burning Emissions (FLAMBE). Results from the simulations are compared with satellite-derived products from the AIRS, MISR and CALIOP sensors. When FLAMBE provides input to the 1-D plume rise model, the resulting injection heights exhibit the best agreement with satellite-observed injection heights. The FLAMBE-derived heights are more realistic than those utilizing prep_chem_sources. Conversely, when the planetary boundary layer or the 3–5 km a.g.l. layer were filled with emissions, the resulting injection heights exhibit less agreement with observed plume heights. Results indicate that differences in injection heights produce different transport pathways. These differences are especially pronounced in area of strong vertical wind shear and when the integration period is long.

scholarly journals Vertical distribution of ozone and VOCs in the low boundary layer of Mexico City

2008 ◽  
Vol 8 (12) ◽  
pp. 3061-3079 ◽  
Author(s):  
E. Velasco ◽  
C. Márquez ◽  
E. Bueno ◽  
R. M. Bernabé ◽  
A. Sánchez ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Mexico City ◽  
Atmospheric Stability ◽  
Ground Level ◽  
Residual Layer ◽  
Background Concentration ◽  
Complex Interactions ◽  
Unstable Layer

Abstract. The evolution of ozone (O3) and 13 volatile organic compounds (VOCs) in the boundary layer of Mexico City was investigated during 2000–2004 to improve our understanding of the complex interactions between those trace gases and meteorological variables, and their influence on the air quality of a polluted megacity. A tethered balloon, fitted with electrochemical and meteorological sondes, was used to obtain detailed vertical profiles of O3 and meteorological parameters up to 1000 m above ground during part of the diurnal cycle (02:00–18:00 h). VOCs samples were collected up to 200 m by pumping air to canisters with a Teflon tube attached to the tether line. Overall, features of these profiles were found to be consistent with the formation of an upper residual layer during nighttime carrying over a fraction of the O3 from the previous day that contributes to the background concentration in surrounding regions. At the same time the release of heat stored in the urban surface forms a shallow unstable layer close to the ground, where the nocturnal emissions are trapped. After sunrise an O3 balance is determined by photochemical production, entrainment from the upper residual layer and destruction by titration with nitric oxide, delaying the ground-level O3 rise by 2 h. The subsequent evolution of the conductive boundary layer and vertical distribution of pollutants are discussed in terms of the energy balance, the presence of turbulence and the atmospheric stability.

scholarly journals INFLUENCE OF SETTLING VELOCITY OF PARTICULATE MATTER ON GROUND LEVEL CONCENTRATIONS

2016 ◽  
Vol 38 ◽  
pp. 560 ◽  
Author(s):  
Tiziano Tirabassi ◽  
Davidson Martin Moreira
Keyword(s):  
Particulate Matter ◽  
Analytical Solution ◽  
Diffusion Equation ◽  
Concentration Distribution ◽  
Settling Velocity ◽  
Atmospheric Stability ◽  
Ground Level ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Ground Level Concentration

The settling velocity and deposition of particulate matter on the earth's surface has been introduced in an analytical solution of advection-diffusion equation. The influence of particle diameters in ground level concentration distribution was investigated in function of different atmospheric stability condiyions 

Environmental Hazards due to Rupture of a Liquefied Propane Pipeline

1996 ◽  
Vol 118 (1) ◽  
pp. 9-15
Author(s):  
O. A. Badr ◽  
H. A. El-Sheikh
Keyword(s):  
Dispersion Model ◽  
Atmospheric Stability ◽  
Ground Level ◽  
Release Time ◽  
Ground Level Concentration ◽  
Dangerous Zone ◽  
Calculated Mass ◽  
Transient Case ◽  
Typical Range ◽  
Vertical Jet

Accidental leakages of liquefied propane from high-pressure pipelines may occur despite the use of sophisticated safety equipment and following strict monitoring procedures. Environmental impact of steady and transient leakages were considered from toxicity and flammability viewpoints for two specific scenarios of full pipe ruptures. For each case, calculated mass flow rate, velocity, and temperature of leaking gas were utilized in an EPA-based dispersion model to predict the ground level concentration profiles in the downwind and crosswind directions. For the specific pipeline conditions considered here, the first scenario of a nonjet release (a cloud) produced steady toxic and flammable zones which were about 20 times bigger than those produced in the transient case. The second scenario of a free vertical jet resulted in the formation of a flammable vertical plume, while at ground level it did not produce flammable nor toxic zones. A parametric study of the first scenario confirmed the expected effects of both the gas release time and the atmospheric stability on the size of the dangerous zones. Within the typical range, the wind speed was found to have opposite effects for steady and transient releases. For a steady release, the dangerous zone was wider for slower winds and vice versa for a transient case. Moreover, the size of the dangerous zone was found to be an exponential function of the pipe diameter, while the effect of the initial pipe pressure was insignificant.

First-Order and Second-Order Sensitivity Studies of ARCON96 for Ground Release Mode

2013 ◽  
Author(s):  
Yun Liu ◽  
Sheng Fang ◽  
Hong Li ◽  
Dong Fang ◽  
Jiejuan Tong ◽  
...  
Keyword(s):  
Wind Speed ◽  
Power Plants ◽  
Input Parameter ◽  
Atmospheric Stability ◽  
Ground Level ◽  
Second Order ◽  
Atmospheric Concentration ◽  
Complete Evaluation ◽  
First Order ◽  
Sensitivity Studies

ARCON96 is the latest USNRC-recommended relative atmospheric concentration calculation program for design basis control room radiological habitability assessments at nuclear power plants. In order to thoroughly evaluate ARCON96 and to provide guidance for ARCON96 implementation, both first and second order systematical sensitivity studies were performed to ARCON96 for ground level release mode. A deterministic Taylor series approximation approach was utilized to analyze the sensitivity of ARCON96 model to wind speed and the distance from the release point to the intake. The sensitivity of ARCON96 was investigated with all atmospheric stability classes for complete evaluation. The results of this study reveal that the sensitivity of ARCON96 is primarily dominated by first-order sensitivity. And the behavior of sensitivity for wind speed and distance is quite different. The computed variance proves the robustness of ARCON96 model in presence of input parameter perturbation.

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