Effective description of Taylor dispersion in strongly corrugated channels.

Abstract

We consider Taylor dispersion in periodic but highly corrugated channels. Exact analytical expressions for the long-time diffusion constant and drift along the channel are derived to next-to-leading order in the limit of a small channel period. Using these results, we show how an effective model for Taylor dispersion in porous media with tortuous pores can be framed in terms of dispersion in a uniform channel with absorption/desorption at its surface, an effective slip length for the flow at the surface, and an effective, universal, diffusion constant on the surface. This work thus extends the concept of an effective slip length for hydrodynamic flows to Taylor dispersion by those flows. The analytical results are confirmed by numerical calculations, and they present a robust method to understand and upscale the transport properties of flows in porelike geometries.