Effects of nanopore geometry on confined water flow: A view of lattice Boltzmann simulation

Water flow in nanoscale channel is demonstrated to be affected by the robust water-wall interactions, including that the flow significantly deviates from the conventional continuum flow. As suggested in different results of experimental observation and simulation in recent literature, nanopores exhibit higher/lower-than-expected flow capacity. Most existing studies are limited to simple geometry that displays a circular cross-section. However, the flow dynamics of water in noncircular pores significantly deviates from the Hagen-Poiseuille flow equation adopted in circular pores that exhibit different contact angles and dimensions. In this study, molecular interactions between water and the solid inner wall are substituted into the formulations of the Lattice Boltzmann method to simulate the flow dynamics in nanopores that exhibit different cross-sectional shapes and wettability. The results show that, under identical crosssectional area injection pressure, the circular nanopore exhibits the maximum flow capacity. In terms of a circular cross-sectional shape, the constant density lines are also circular and concentric. For angular cross-sectional shape, the constant density lines do not comply with the cross-sectional shape, and the density varies significantly at the corner. The effects of geometry and density distribution of different contact angles are elucidated. An empirical formula under different geometry and wettability has been established, which is of high significance in modeling water flow in various engineering nano-systems such as shale matrix, membrane, and aquaporins. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Water flow in nanoscale channels is affected by strong water-wall interactions, leading to deviations from conventional continuum flow. Different cross-sectional shapes and wettability of nanopores significantly impact flow dynamics, with circular nanopores showing maximum flow capacity under identical injection pressure. Empirical formulas have been established to model water flow in various engineering nano-systems.