The Theory of Three-dimensional Turbulent Diffusion

The three-dimensional diffusion of minute particles emitted from a point source is discussed in close connection with the energy spectrum of the isotropic and homogeneous turbulence, and it is shown that the feature of the diffused cloud near the source is controlled solely by the energy spectrum in the intermediate wave-number range.Moreover, an approximate representation for statistical quantities which appear frequently in the turbulence theory is presented.