Effect of meniscus constact angle during early regimes of spontaneous capillarity in nanochannels

N.K. Karna, Elton Oyarzua, Jens Honore Walther, Harvey Zambrano

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Abstract

In capillary imbibition, the classical Lucas-Washburn equation predicts a singularity as the fluid enters the channel con-sisting in an anomalous innite velocity of the capillary meniscus. The Bosanquets equation overcomes this problem by taking into account fluid inertia predicting an initial imbibition regime with constant velocity. Nevertheless, the initial constant velocity predicted by Bosanquet's equation is much greater than experimentally observed. In the present study, we conduct atomistic simulations to investigate capillary imbibition of water in silica nanochannels with heights between 4 and 18 nm. We alsofind that the meniscus contact angle remains constant during the inertial regime and its value depends upon the height of the channel. We also find that the meniscus velocity computed at the channel entrance is related to the particular value of themeniscus contact angle. Moreover, after the inertial regime, the meniscus contactangle is found to be time dependent for all the channels under study. We propose an expression for the time evolution of the dynamic contact angle in nanochannels which, when incorporated in Bosanquets equation, satisfactorily explains the initial capillary rise.
Original languageEnglish
Title of host publicationBulletin of the American Physical Society
Number of pages1
Volume61
PublisherAmerican Physical Society
Publication date2016
Article numberA22.00007
Publication statusPublished - 2016
Event69th Annual Meeting of the APS Division of Fluid Dynamics - Portland, United States
Duration: 20 Nov 201622 Nov 2016

Conference

Conference69th Annual Meeting of the APS Division of Fluid Dynamics
CountryUnited States
CityPortland
Period20/11/201622/11/2016

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