Journal of Statistical Physics, Vol. 61, Nos. 3/4, 1990, p. 589-605.
We discuss intermittency effects in the distribution of scalar passive impurities within fully developed hydrodynamic turbulence. It is shown that the observable stronger intermittency effects in the distribution of passive impurities with respect to that for the energy dissipation rate can naturally be explained in the framework of composite random cascade models. We discuss doubly random bounded and unbounded log-normal models, the doubly random beta-model, and the two-scale Cantor set approximation. Then the problem of mutual correlations is discussed. The various results are compared with experiments.