EXPERIMENTAL MEASUREMENTS OF CONCENTRATION FLUCTUATIONS AND SCALES IN A DISPERSING PLUME IN THE ATMOSPHERIC SURFACE LAYER OBTAINED USING A VERY FAST RESPONSE CONCENTRATION DETECTOR

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Authors
  1. Yee, E.
  2. Chan, R.
  3. Kosteniuk, P.R.
  4. Chandler, G.M.
  5. Biltoft, C.A.
  6. Bowers, J.F.
Corporate Authors
Defence Research Establishment Suffield, Ralston ALTA (CAN);Kosteniuk Consulting Ltd, Saskatoon SASK (CAN)
Abstract
High-frequency fluctuations of concentration in a plume dispersing in the atmospheric surface layer have been measured with high-resolution concentration detectors (approximately 270 Hz at the - 6-dB point) to extract various concentration statistics of the fluctuating concentration field. Crosswind and alongwind variations of amplitude statistics (e.g., the total and conditional fluctuation intensity, skewness, and kurtosis), the intermittency factor, and the shapes of the concentration probability density fuction (PDF) are presented. The behavior of temporal concentration statistics such as the autocorrelation function; power spectrum; PDF of upcrossing intervals; PDF of exursion durations; various concentration timescales, length scales, and microscales (e.g., Taylor microscale, correlation scale, length scale based on the spectral peak, etc.); as well as the velocity-to-concentration timescale ratio are studied. It is shown that all the concentration length scales and microscales (with the exception of the correlation scale) grow with downwind distance in proportion to the mean plume width.
Date of publication
08 Aug 1994
Number of Pages
22
DSTKIM No
95-02465
CANDIS No
148750
Format(s):
Document Image stored on Optical Disk;Hardcopy

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