PROBABILITY DENSITY FUNCTION OF CONCENTRATION INCREMENTS IN A SURFACE PLUME DISPERSING IN THE ATMOSPHERIC BOUNDARY LAYER

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Authors
  1. Chan, E.Y.R.
Corporate Authors
Defence Research Establishment Suffield, Ralston ALTA (CAN)
Abstract
The probability density function (PDF) of passive scalar concentration increments, delta psi (r), across scales r in the inertial-convective subrange has been measured for a plume dispersing in the atmospheric surface layer at a large Taylor microscale based Reynolds number R lambda = 5200. The PDF possesses a characteristic non-Gaussian form with extended exponential tails that increase with decreasing scale. For moderately large (delta psi (r)), the PDF scales in accordance to a stretched exponential from P(delta psi) - exp(-k(r)/delta psi/qr), with a tail slope q(r) (stretching exponent) and tail intercept k(r) (logarithmic decrement) that monotonically increases and decreases, respectively, for increasing scales r within inertial-convective subrange. Both q(r) and k(r) are found to be well-characterized using power-law relationships in r (viz., q(r) approximates to r super a and k(r) approximates r super b), and the power-law exponents a and b in these two relationships have been empirically determined from the data. Measurements of skewness and kurtosis of the concentration increments have been obtained for a wide range of scales r. TRUNCATED
Keywords
Surface plumes
Date of publication
31 Dec 1996
Number of Pages
12
Reprinted from
Physics Letters A, vol 227, 1997, p 340-348
DSTKIM No
97-03878
CANDIS No
503188
Format(s):
Hardcopy;Document Image stored on Optical Disk

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