Continuum concepts in nanoscale capillary impregnation

Henrich, B.; Cupelli, Claudio; Santer, Mark; Moseler, Michael

doi:10.1088/1367-2630/10/11/113022

Cited by 22 publications

(23 citation statements)

References 44 publications

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“…Also the fact that τ v ∼ 1-10 ns indicates that the viscosity-dependent (or Washburn) regime will be observed over this time scale (which is much larger than the time scales accessed in Refs. [16,17]), as indicated by other MDS results [13,22,33,34].…”

Section: Resultssupporting

confidence: 61%

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Early regimes of capillary filling

Das

Waghmare²,

Mitra³

2012

Phys. Rev. E

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In this paper we analyze the inviscid regime (for which viscosity is unimportant and the flow occurs due to the balance between the capillary and the inertial effects) that invariably precedes the classical century-old Washburn regime during capillary filling. We demonstrate that a new nondimensional number, namely, the product of the Ohnesorge number and the ratio between the filling length (ℓ) and the radius of the capillary (R), dictates the occurrence of this regime and the other well-known regimes in a capillary filling problem. We also identify that this inviscid regime occurs for the time that is of the order of the capillary time scale and, as has been quantified before [Quere, Eur. Phys. Lett. 39, 533 (1997); Joly, J. Chem. Phys. 135, 214705 (2011)], is characterized by the filling length being linearly proportional to the filling time. We establish the universality of this regime by pinpointing the existence of this regime (showing appropriate dependencies of the capillary radii and density) from existing experimental and Molecular Dynamics Simulation results that signify disparate ranges of length and time scales.

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Section: Resultssupporting

confidence: 61%

“…The other spectrum of capillary filling problems, which deal with much smaller time scales (picoseconds to nanoseconds) are the MDS studies on capillary imbibition [13,16,17,22]. In these studies R ∼ 1 nm and u 0 ∼ 100 m/s [16,17] (attributed to large slip lengths [23][24][25]).…”

Section: Resultsmentioning

confidence: 99%

Early regimes of capillary filling

Das

Waghmare²,

Mitra³

2012

Phys. Rev. E

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“…60 As shown in ref 61, a detailed LB−molecular dynamics comparison requires subnanoscopic spatial resolution, and consequently such prospective simulations will necessarily be restricted to much shorter channels than those considered in this paper. …”

Section: ■ Conclusionmentioning

confidence: 99%

Interplay between Shape and Roughness in Early-Stage Microcapillary Imbibition

Girardo¹,

Palpacelli

Maio

et al. 2012

Langmuir

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Flows in microcapillaries and associated imbibition phenomena play a major role across a wide spectrum of practical applications, from oil recovery to inkjet printing and from absorption in porous materials and water transport in trees to biofluidic phenomena in biomedical devices. Early investigations of spontaneous imbibition in capillaries led to the observation of a universal scaling behavior, known as the Lucas-Washburn (LW) law. The LW allows abstraction of many real-life effects, such as the inertia of the fluid, irregularities in the wall geometry, and the finite density of the vacuum phase (gas or vapor) within the channel. Such simplifying assumptions set a constraint on the design of modern microfluidic devices, operating at ever-decreasing space and time scales, where the aforementioned simplifications go under serious question. Here, through a combined use of leading-edge experimental and simulation techniques, we unravel a novel interplay between global shape and nanoscopic roughness. This interplay significantly affects the early-stage energy budget, controlling front propagation in corrugated microchannels. We find that such a budget is governed by a two-scale phenomenon: The global geometry sets the conditions for small-scale structures to develop and propagate ahead of the main front. These small-scale structures probe the fine-scale details of the wall geometry (nanocorrugations), and the additional friction they experience slows the entire front. We speculate that such a two-scale mechanism may provide a fairly general scenario to account for extra dissipative phenomena occurring in capillary flows with nanocorrugated walls.

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“…We assume the meniscus to have a hemispherical shape (see 5), therefore the discrete interface was approximated by a circular arc. A circular arc is shown to be appropriate to fit the meniscus 14,25,31,32,37,40 apart from a region very close to the wall where, especially in the case of a prewetting layer existence, some deviations can occur.…”

Section: Transient Regimementioning

confidence: 99%

Spontaneous Imbibition in Nanopores of Different Roughness and Wettability

Stukan¹,

Ligneul²,

Crawshaw³

et al. 2010

Langmuir

106

107

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The spontaneous imbibition of liquid in nanopores of different roughness is investigated using coarse grain Molecular Dynamics (MD) simulation. The numerical model is presented and the simplifying assumptions are discussed in detail. The molecular-kinetic theory introduced by Blake is used to describe the effect of dynamic contact angle on fluid imbibition. The capillary roughness is modeled using a random distribution of coarse grained particles forming the wall. The Lucas-Washburn equation is used as a reference for analyzing the imbibition curves obtained by simulation. Due to the statistical nature of MD processing, a comprehensive approach was made to average and smooth the data to accurately define a contact angle. The results are discussed in terms of effective hydrodynamic and static capillary radii and their difference as a function of roughness and wettability.

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Continuum concepts in nanoscale capillary impregnation

Cited by 22 publications

References 44 publications

Early regimes of capillary filling

Early regimes of capillary filling

Interplay between Shape and Roughness in Early-Stage Microcapillary Imbibition

Spontaneous Imbibition in Nanopores of Different Roughness and Wettability

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