This article addresses the application of pulsed system models (in which the advection operator is decoupled from the diffusion operator) for investigating the physics of dispersion/ homogenization in deterministic chaotic flows. The analysis is organized along to main directions: (i) the development of a simplified time-continuous model which can be viewed as a generalization in a time-continuous frame of the baker's transformation, and which is amenable to analytical investigation, and (ii) the comparison of the results deriving from several typical pulsed-system models with the direct numerical simulation of the advection diffusion equation. Both these approaches reveal the intrinsic ambiguity of the pulsed system approach in describing advection-diffusion problems. (C) 2004 Elsevier B.V. All rights reserved.