Early Regimes of Water Capillary Flow in Slit Silica Nanochannels

Elton Oyarzua, Jens Honore Walther, Andres Mejia, Harvey Zambrano

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Molecular dynamics simulations are conducted to investigate the initial stages of spontaneous imbibitionof water in slit silica nanochannels surrounded by air. An analysis is performed for the effects of nanoscopicconfinement, initial conditions of liquid uptake and air pressurization on the dynamics of capillaryfilling. The results indicate that the nanoscale imbibition process is divided into three main flow regimes:an initial regime where the capillary force is balanced only by the inertial drag and characterized by aconstant velocity and a plug flow profile. In this regime, the meniscus formation process plays a centralrole in the imbibition rate. Thereafter, a transitional regime takes place, in which, the force balance hassignificant contributions from both inertia and viscous friction. Subsequently, a regime wherein viscousforces dominate the capillary force balance is attained. Flow velocity profiles identify the passage froman inviscid flow to a developing Poiseuille flow. Gas density profiles ahead of the capillary front indicatea transient accumulation of air on the advancing meniscus. Furthermore, slower capillary filling ratescomputed for higher air pressures reveal a significant retarding effect of the gas displaced by the advancing meniscus.
Original languageEnglish
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number22
Pages (from-to)14731-14739
ISSN1463-9076
DOIs
Publication statusPublished - 2015

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