How pore geometry affects the transition of non-Fickian to Fickian solute transport over various length scales03/21/2019
Pore scale solute transport is known to exhibit non-fickian solute transport characteristics related to pronounced tailing during asymptotic times. The tailing behavior is likely associated with large variability in pore fluid velocity, which is caused by diverging-converging pore channel geometry, and which further is magnified during inertial flows, as eddies or ‘recirculation zones’ form and grow in the dead-end part of pore channels. In this study we, at first, design a series of pore channel geometries and define them with a non-dimensional pore geometry parameter ‘γ’. We use these geometries to solve Navier-Stokes and Advection-Diffusion (ADE) equations and obtain ‘break through curves’. These curves are used to fit analytical solution to ADE and determine the degree of non-fickian to fickian transport characteristics for various range of Reynolds number (Re) flows. Finally, pore channels are systematically extended in the direction of flow to ‘length scales’ where the non-Fickian transport becomes Fickian transport. The relationships between ‘γ’, Re, and length scales for Fickian transport will be presented during the conference meeting.