A SIMPLE MODEL FOR THE PROBABILITY DENSITY FUNCTION OF CONCENTRATION FLUCTUATIONS IN ATMOSPHERIC PLUMES

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Authors
  1. Yee, E.
  2. Chan, R.
Corporate Authors
Defence Research Establishment Suffield, Ralston ALTA (CAN)
Abstract
Simple closure hypotheses for the conditional pseudo-diffusion and pseudo-dissipation terms given a fixed concentration level in a dispersing plume are formulated, and used to obtain a simple functional form for the one-point probability density function (PDF) of concentration. These closure assumptions lead to a left-shifted and clipped-gamma PDF. A simple parametric expression for the observed relationship between the intermittency factor (i.e. the probability of non-zero concentrations) and the normalized second concentration moment is incorporated in the specification of the clipped-gamma PDF. This expression allows the form of the clipped-gamma PDF to be completely specified in terms of only two parameters; namely, the mean concentration and concentration variance. Comparisons of the clipped-gamma PDF to some atmospheric and large-eddy simulation concentration data show good agreement over a wide range of plume locations and atmospheric conditions.
Keywords
Atmospheric dispersion models;Plume dispersion;Plume concentration statistics;Hazard assessment
Report Number
DRES-RP-95-021 — Reprint
Date of publication
16 Aug 1996
Number of Pages
12
Reprinted from
Atmospehric Environment, vol 31, no 7, 1997, p 991-1002
DSTKIM No
97-01362
CANDIS No
501799
Format(s):
Hardcopy;Document Image stored on Optical Disk

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