Dispersion in a two-zone packed tube: An extended Taylor’s analysis

Taylor’s classical analysis for scalar dispersion in a single phase fluid flow is rigorously generalized for an instantaneous release of scalar substances into a fully developed flow through a long tube of two zones distinctively packed with porous media. A formulation for the dispersion is presented by cross-sectionally averaging the concentration transport equations and introducing a closure model for the concentration deviation terms produced in the averaging procedure. The velocity distribution of the flow through the tube is derived, with existing solution for a single zone tube flow included as a special case. Corresponding dispersivity is analytically determined, and Taylor’s well-known result for a single phase flow in a single-zone tube is recovered by setting corresponding parameters as unity. The effects of relevant parameters on both velocity profile and Taylor dispersivity are illustrated.

► To present a formulation for dispersion in a two-zone packed tube by extending Taylor’s classical analysis. ► To give a velocity distribution of superficial flow through the tube. ► To determine the dispersivity in the tube. ► To characterize the skewness of the velocity profile and corresponding enhancement of the dispersivity by relevant dimensionless parameters.