Turbulent relative dispersion

This review begins with the classical foundations of relative dispersion in Kolmogorov's similarity scaling. Analysis of the special cases of isotropi c and homogeneous scalar fields is then used to establish most simply the c onnection with turbulent mixing. The importance of the two-particle acceler ation covariance in relative dispersion is demonstrated from the kinematics of the motion of particle-pairs. A summary of the development of two-parti cle Lagrangian stochastic models is given, with emphasis on the assumptions and constraints involved, and on predictions of the scalar variance field for inhomogeneous sources. Two-point closures and kinematic simulation are also reviewed in the context of their prediction of the Richardson constant and other fundamental constants. In the absence of reliable field data, di rect numerical simulations and laboratory measurements seem most likely to provide suitable data with which to test the assumptions and predictions of these theories.