A SIMPLE REPRESENTATION OF A DEVELOPING CONTAMINANT CONCENTRATION FIELD

Chatwin & Sullivan (1990) have demonstrated that, for a wide range of self-similar scalar fields, the moments of the probability density fun ction of concentration have a very simple form. Here, an extension to this simple form which takes account of the source distribution is dev eloped. This extension has two effects. Firstly it modifies the values of the two parameters appearing in the original theory and in particu lar explains the observed behaviour of these parameters very near to a line source of heat in grid tubulence. Secondly, it introduces an add itional parameter in the description of each moment beyond the second. It is shown that these additional parameters are necessary in order t o describe measurements of the first four central moments throughout t he concentration field from a continuous line source of heat in grid-g enerated turbulence.