Predicting the spatial distribution of concentration fluctuations from a ground level source

Wilson, David J.; Robins, Alan; Fackrell, J.E.

doi:10.1016/0004-6981(82)90158-5

Cited by 39 publications

(18 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…That study was based on data from a rough-walled boundary layer, with propane as the contaminant in neutrally buoyant mixtures, using a fast response flame ionization detector system (Wilson et al 1982). We obtained experimental results for the fixed frame normalized concentration variations, skewness and kurtosis, respectively.…”

Section: Fixed Framementioning

confidence: 99%

Concentration Fluctuations in Smoke Plumes Released Near the Ground

Jørgensen

Mikkelsen

Pécseli

2010

Boundary-Layer Meteorol

View full text Add to dashboard Cite

Near-ground artificial cloud releases in the turbulent atmospheric boundary layer were investigated experimentally by Lidar measurement techniques. Simple scaling relations between the average concentration and the lowest order moments are suggested by simple analytical models, and the experimental results are tested against these hypotheses. We find strong evidence for a simple scaling of the standard deviation, skewness and kurtosis with the average concentrations at the downwind distances observed in our experiments. Near-ground concentration fluctuations in fixed as well as moving frames of references are investigated. The scaling is supported by data from several experimental sites and different atmospheric stability conditions. One conclusion of the study is that relatively accurate estimates for the standard deviation, skewness and kurtosis can be obtained for the concentration fluctuations, given a reliable estimate of the space-time varying average concentration field.

show abstract

Section: Fixed Framementioning

confidence: 99%

Concentration Fluctuations in Smoke Plumes Released Near the Ground

Jørgensen

Mikkelsen

Pécseli

2010

Boundary-Layer Meteorol

View full text Add to dashboard Cite

show abstract

“…The concentration variance ratio, (c~)O.~//C~, is plotted versus dimensionless downwind distance, x*, in Figure 13. Notice that for the smallest cup (smallest density effects) the ratio seems to approach a limit between 0.5 and 0.35 similar to the behavior of passive plumes discussed by Wilson et al (1982). Larger volumes generate larger gravity forces and the upper limit of the ratio declines to levels between 0.2 and 0.1.…”

Section: Concentration Variance Behaviormentioning

confidence: 72%

“…Wilson et al (1982) found that the maximum root-mean-square to mean concen--tration ratio, (c')O.~/C~, generally lies between 0.6 and 0.4 for a ground-level neutral density source, the variation depending on downwind distance. They also reported vertical profiles of variance which have a maximum displaced slightly above the ground surface.…”

Section: The Variance Of Concentration Fluctuationsmentioning

confidence: 99%

See 1 more Smart Citation

Statistical characteristics of instantaneous dense gas clouds released in an atmospheric boundary-layer wind tunnel

Meroney

Lohmeyer

1984

Boundary-Layer Meteorol

View full text Add to dashboard Cite

Wind tunnel experiments were performed to examine the behavior of suddenly released volumes of dense gas in a turbulent shear layer. Instantaneous concentrations were measured with hot-wire katherometers. Multiple replications of each cloud volume, density, and velocity combination produced statistics for plume arrival time, arrival of maximum concentration time, plume departure time, and maximum concentrations. Probability distributions and standard deviations of each plume property permit prediction of hazard risks.

show abstract

“…Analysis of the fluctuating concentration field has been based on full scale experiments [3][4][5], small scale models in wind tunnels [6][7][8][9][10] and in water channels [11,12]. Models have been developed to evaluate the intensity of fluctuations and the statistics of exceeding specific concentration thresholds [13][14][15][16][17][18]. Remote-sensing with LIDAR systems has also been used to characterize fluctuations in full scale plumes [19,20].…”

Section: Introductionmentioning

confidence: 99%

Statistical properties of concentration fluctuations in two merging plumes

2013

View full text Add to dashboard Cite

The statistics of the fluctuating concentration field within a plume is important in the analysis of atmospheric dispersion of toxic, inflammable and odorous gases. Previous work has tended to focus on concentration fluctuations in single plumes released in the surface layer or at ground level and there is a general lack of information about the mixing of two adjacent plumes and how the statistical properties of the concentration fluctuations are modified in these circumstances. In this work, data from wind tunnel experiments are used to analyse the variance, skewness, kurtosis, intermittency, probability density function and power spectrum of the concentration field during the mixing of two identical plumes and results are compared with those obtained for an equivalent single plume. The normalised variance, skewness and kurtosis on the centre-lines of the combined plume increase with distance downwind of the stack and, in the two-source configuration, takes lower values than those found in the single plumes. The results reflect the merging process at short range, which is least protracted for cases in which the sources are in-line or up to 30 • off-line. At angles of 45 • and more, the plumes are effectively side-by-side during the merging process and the interaction between the vortex pairs in each plume is strong. Vertical asymmetry is observed between the upper and the lower parts of the plumes, with the upper part having greater intermittency (i.e. the probability that no plume material is present) and a more pronounced tail to the concentration probability distribution. This asymmetry tends to diminish at greater distances from the source but occurs in both buoyant and neutral plumes and is believed to be associated with the 'bending-over' of the emission in the cross-flow and the vortex pair that this generates. The results allowed us to identify three phases in plume development. The first, very near the stack, is dominated by turbulence generated within the plume and characterised by concentration spectra with distinct peaks corresponding to scales comparable with those of the counter-rotating vortex pair. A second phase follows at somewhat greater distances 123Environ Fluid Mech downwind, in which there are significant contributions to the concentration fluctuations from both the turbulence internal to the plume and the external turbulence. The third phase is one in which the concentration fluctuations appear to be controlled by the external turbulence present in the ambient flow.

show abstract

Predicting the spatial distribution of concentration fluctuations from a ground level source

Cited by 39 publications

References 8 publications

Concentration Fluctuations in Smoke Plumes Released Near the Ground

Concentration Fluctuations in Smoke Plumes Released Near the Ground

Statistical characteristics of instantaneous dense gas clouds released in an atmospheric boundary-layer wind tunnel

Statistical properties of concentration fluctuations in two merging plumes

Contact Info

Product

Resources

About