Filling of charged cylindrical capillaries

Das, Siddhartha ; Chanda, Sourayon ; Eijkel, J. C. T. ; Tas, N. R. ; Chakraborty, Suman ; Mitra, Sushanta K. (2014) Filling of charged cylindrical capillaries Physical Review E, 90 (4). Article ID 043011. ISSN 1539-3755

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Official URL: http://journals.aps.org/pre/abstract/10.1103/PhysR...

Related URL: http://dx.doi.org/10.1103/PhysRevE.90.043011

Abstract

We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because of decreased velocity gradients at the wall. Both these effects essentially stem from the spontaneous formation of an electric double layer (EDL) and the resulting streaming potential caused by the net capillary-flow-driven advection of ionic species within the EDL. Our results demonstrate that filling of charged capillaries also exhibits the well-known linear and Washburn regimes witnessed for uncharged capillaries, although the filling rate is always lower than that of the uncharged capillary. We attribute this to a competitive success of the lowering of the driving forces (because of electroviscous effects), in comparison to the effect of weaker drag forces. We further reveal that the time at which the transition between the linear and the Washburn regime occurs may become significantly altered with the introduction of surface charges, thereby altering the resultant capillary dynamics in a rather intricate manner.

Item Type:Article
Source:Copyright of this article belongs to The American Physical Society.
ID Code:100362
Deposited On:10 Nov 2016 10:30
Last Modified:10 Nov 2016 10:30

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