Revealing nanoscale slip within Taylor–Aris dispersion

Abstract

Hydrodynamic slip at fluid–solid interfaces plays an important role in a range of transport phenomena, especially in fluids under small-scale confinement. Much work has studied the microscopic origins of slip. In this work, we explore the connection between the microscopic slip velocity and the macroscopic (slip-adjusted) Taylor–Aris dispersion in the fluid, which enables the former to be written in terms of the latter. Through extensive molecular-dynamics simulations of simple and polymeric fluids under a wide range of thermodynamic and geometric conditions, we show that the continuum treatment of Taylor–Aris dispersion can be readily extended to systems where the confining length-scale is comparable to the slip length. We further demonstrate that slip velocity can be accurately inferred through measurements of equilibrium and shear-augmented molecular self-diffusivities.