The effects of imperfect spatial resolution on the experimental determination of the probability density function of concentration in turbulent diffusion
Abstract
The paper deals with a cloud of passive contaminant released in a turbulent flow, and, in particular, with the probability density function of concentration. (Thus pdGamma is the probability that, at position x and time t, the concentration is between Gamma and Gamma + dGamma). On the basis of previous theoretical and experimental work, typical forms of p are discussed qualitatively. Furthermore, the effects of the inevitable imperfect spatial resolution present in experiments is shown to lead to important discrepancies between the measured and actual values of p. Some consequences of these discrepancies are interpreted in terms of the real behavior of a dispersing cloud. Attention is focused particularly on the median concentration, introduced by the authors in their contribution to the 5th Biennial Symposium in 1977, and on a 'stringiness factor' measuring the extent to which the cloud has been drawn out into a long thread.
 Publication:

6th Biennial Symposium on Turbulence
 Pub Date:
 1979
 Bibcode:
 1979btur.symp....7C
 Keywords:

 Concentration (Composition);
 Probability Density Functions;
 Resolution;
 Turbulent Diffusion;
 Clouds;
 Contaminants;
 Nonuniform Flow;
 Fluid Mechanics and Heat Transfer