Abstract
The dispersion of a passive scalar advected by a turbulent incompressible flow characterized by inhomogeneous and nonstationary statistics is investigated by expanding the velocity and scalar concentration fields in Wiener-Hermite functions. The time evolution equation for the ensemble mean concentration is determined in terms of Eulerian one-point, two-time and one-point, three-time correlation functions defined in the coordinate frame moving with the mean velocity. The example of a plane-parallel mean flow is studied in detail and eddy diffusivity tensors are extracted from the formalism.
