Wake effect, building

Huber, A. H., and Snyder, W. H., Building wake effects on short stack effluents, pp. 235-242 in Preprints, Third Symposium on Atmospheric Turbulence, Diffusion and Air Quality. October 19-22, 1976, Raleigh, NC. American Meteorological Society, Boston, 1976. 

The modeling package, delivered to the EPA, includes nationwide data bases for emissions, dispersion meteorology, and population patterns. These data are used as input for a Gaussian plume model for point sources and a box model for urbanwide area sources. Prototype modeling is used for point sources that are too numerous to define individually. Building wake effects and atmospheric chemical decay are addressed. 

Huber, A. H., Incorporating building/terrain wake effects on stack effluents, pp. 353-356 in Preprints, Joint Conference on Applications of Air Pollution Meteorology. November 29-December 2, 1977, Salt Lake City, UT. American Meteorological Society, Boston, MA, 1977. 

Figure 2.10 Characteristic dispersion mechanisms in canopies from local sources close to an isolated obstacle source outside wake/canyon, showing impaction of the plume from Source (1), wake entrainment (E) and detrainment (D) from Sources 1 and 2. Note how the plume profile G(z) has a split structure in the wake with unentrained component Gp0 and detrained component Gpw. Gc denotes the typical outline of a cloud emitted upwind, showing the additional longitudinal dispersion associated with the blocking and wake effects. Here the reference cloud outline in the absence of buildings is shown as a dashed line with small circles, with streamwise dimension crj0.

Ejfective Height of an Emission The effective height of an emission rarely corresponds to the physical height of the stack. If the plume is caught in the turbulent wake of the stack or of buildings in... 

The effective height of an emission rarely corresponds to tlie physical height of tlie source or the stack. If tlie plume is caught in tlie turbulent wake of tlie stack or of buildings in the vicinity of tlie source or stack, tlie effluent will be mixed rapidl) downward toward the ground. If the plume is emitted free of these turbulent zones, a number of emission factors and meteorological factors influence tlie rise of the plume. 

In the 1920s and 1930s, Kleitman studied the effects of sleep deprivation (22) and concluded that the build-up of endogenous sleep factors did not exceed certain limits, and humans became as impaired as they would get after approximately 2.5 days of wakefulness. 

When there are marked variations in the height of adjacent obstacles, the wake vorticity shed from upwind buildings can produce sharp down-flows and increased trailing vorticity in the flow direction, (see Lawson, 1980 [360]). These effects contribute to mixing between the canopy and external flow, Figure 2.6. When tall cuboid obstacles are closely packed (i.e. H/w > 1, b/d > 1/2), as the air flow passes around them the wakes tend to disappear (because of cancellation of vorticity) and the streamlines are determined simply by the displacement or blocking effects of the buildings (Davidson et al., 1995 [143] Moulinec et al., 2003 [436]). 

This shows that if crv/C/c = 1/10, then b/d > 1/4 for the topological spreading to be greater than the turbulent diffusion. When bid <1/3 the spreading effect by the wakes (as described in Section 2.4.2 above) is an additive effect. But when b/d > 1/3, the converging flow between the buildings tends to reduce the sizes of... 

Caffeine is one of a group of substances called methylxanthines. They are closely similar compounds to adenine and guanine, which are building blocks in the nucleotides AMP, ADP, ATP and GMP, GDP and GTP. Caffeine is the main stimulant substance in coffee but similar compounds, theophylline and theobromine, are found in cocoa and tea. All of them promote wakefulness. Caffeine is the stimulant in such drinks as Red Bull. One of the sites of action of these substances is the enzyme cAMP phosphodiesterase, where they act as inhibitors (see Appendix 13). This effectively keeps the systems that are activated by cAMP switched on. It is now known also that these compounds have another site of action in the brain and elsewhere. In these locations there are inhibitory adenosine receptors, upon which caffeine acts as an antagonist. 

It is assumed that the plume is emitted with a velocity sufficient to escape the downwash effects of the wake behind the chimney. It is also assumed that the chimney is of sufficient height, and the terrain is sufficiently level, so that the effects of buildings and terrain can be neglected. Upon leaving the chimney, the plume usually encounters a crosswind which causes the plume to bend. The effect on the plume can be described in the following stages ... 

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