Multiscale Model for Electrokinetic Transport in Networks of Pores, Part II: Computational Algorithms and Applications

Abstract

The first part of this two-article series presented a robust mathematical model for the fast and accurate prediction of electrokinetic phenomena in porous networks with complex topologies. In the second part of this series, we first present a numerical algorithm that can efficiently solve the model equations. We then demonstrate that the resulting framework is capable of capturing a wide range of transport phenomena in microstructures by considering a hierarchy of canonical problems with increasing complexity. The developed framework is validated against direct numerical simulations of deionization shocks in micropore-membrane junctions and concentration polarization in micro- and nanochannel systems. We demonstrate that for thin pores subject to concentration gradients our model consistently captures correct induced osmotic pressure, which is a macroscopic phenomena originally derived from thermodynamic principles but here is naturally predicted through microscopic electrostatic interactions. Moreover, we show that the developed model captures current rectification phenomena in a conical nanopore subject to an axial external electric field. Finally, we provide discussions on examples involving stationary and moving deionization shocks in micropore nanopore T-junctions as well as induced-flow loops when pores of varying sizes are connected in parallel.

Surface conduction and electroosmotic flow around charged dielectric pillar arrays in microchannels

“…This is directly associated with overlimiting conductance. The role of SC, EOF and EOI become distinguishable in overlimiting current regime as several literatures predicted and verified 5,6,20,[64][65][66][67][68] . This means I-V responses should be identical in under limiting current regime, especially when the surface area (for the same surface conduction) and cross-sectional area (for the same bulk conduction) of microchannel are kept to be constant.…”

Spontaneous diffusiophoretic separation in paper-based microfluidic device

“…This is contradictory to our present observation [13] and it may come due to the complex geometry of cellulose and interaction of particles with it. In the random (or natural) pore network, various convective flow such as recirculation can be included in the analysis [20][21][22][23]. Thus, one need further investigations for the exact fundamentals in paper-based device.…”

Impact of network heterogeneity on electrokinetic transport in porous media

“…In our previous two-paper series, 46,47 we presented comprehensive derivation and validation of our multi-scale model that enables pore-scale simulation of nonlinear electrokinetic phenomena in porous structures. We model a porous structure as a network of micro-scale and nano-scale pores, each is to be long and thin.…”