On the dynamical origin of asymptotic t^2 dispersion of a nondiffusive tracer in incompressible laminar flows
Using an elementary application of Birkhoff's ergodic theorem, necessary and sufficient conditions are given for the existence of asymptotically t^2 dispersion of a distribution of nondiffusive passive tracer in a class of incompressible laminar flows. Nonergodicity is shown to be the dynamical mechanism giving rise to this behavior.
Copyright © 1994 American Institute of Physics (Received 17 December 1993; accepted 24 February 1994) We would like to thank John Brady for a critical reading of this note. This work was supported by an NSF Presidential Young Investigator Award, ONR Grant No. N00014-89-J-3023, and AFOSR Grant No. AFOSR910241.