We show a purely coarse-grained model for Taylor dispersion based on extended irreversible thermodynamics which captures the main features of Taylor dispersion along all the time span: asymptotic diffusive behavior, transient anisotropy, incorporation of transverse initial conditions, and transition to irreversibility. The macroscale model equation is recovered from an analysis in the detailed three-dimensional space, and its predictions for the lowest moments of the solute concentration are satisfactorily compared with numerical simulations at all times for initial distributions sufficiently spread along the tube section. Special attention is paid to the transition to irreversibility in Taylor dispersion.

• Received 11 January 1993

DOI:https://doi.org/10.1103/PhysRevE.48.310