Dynamics of hemiwicking

Kim, Jung‐Chul; Moon, Myoung‐Woon; Kim, Ho-Young

doi:10.1017/jfm.2016.386

Cited by 71 publications

(79 citation statements)

References 19 publications

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“…For drainage processes with M > 1, roughness has been shown to induce incomplete displacement, a phenomenon featured by the nonwetting phase advancing along the center of the void space, leaving a trailing film of the wetting phase on the wall (Chen, Wu, et al, ). In imbibition, the roughness may lead to wicking of wetting (secondary) film into the substrates with patterned grooves (Kim et al, ; Quéré, ; Rye et al, ). Here from supporting information Movies S1 and S2, we do not observe the wicking of secondary film, which may be attributed to the rough surfaces of the rock fracture with strong heterogeneity.…”

Section: Resultsmentioning

confidence: 99%

Energy Conversion Reveals Regime Transition of Imbibition in a Rough Fracture

Yang

et al. 2018

Geophysical Research Letters

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As externally imposed flow rate increases during imbibition, viscous force increasingly dominates displacement over capillarity and imbibition shifts from capillary to capillary‐viscous regimes. Previous studies focused on capillary regime, lacking a fundamental understanding of regime transition. Here we study the imbibition transition via flow rate‐controlled experiments in a rough fracture. By analyzing energy balance in multiphase flow system, we find a fundamental link between regime transition and energy conversion. In capillary regime, surface energy is partially transformed into external work and an amount of 51−58% is dissipated via local rapid, irreversible events; while in capillary‐viscous regime, surface energy together with external work is transformed into kinetic and dissipated energies. This transition, corresponding to critical capillary number, is evidenced by quantitative analysis of invasion morphologies. Our work bridges the gap between energy conversion/dissipation and multiphase flow and has important implications for identifying imbibition regimes in enhanced oil recovery and geological CO2 sequestration.

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Section: Resultsmentioning

confidence: 99%

Energy Conversion Reveals Regime Transition of Imbibition in a Rough Fracture

Yang

et al. 2018

Geophysical Research Letters

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“…Liquid transport on a superoleophilic track is determined by multiple parameters, the most important being wettability contrast (i.e., difference in wettability between inner and outer regions), surface roughness (affecting hemiwicking), and liquid properties (e.g., γ and µ ). For a fixed material system, transport performance is dependent primarily on the liquid surface tension (driving force).…”

Section: Resultsmentioning

confidence: 99%

Fluorinated Nanocomposite Coatings for Confinement and Pumpless Transport of Low‐Surface‐Tension Liquids

Morrissette

Ghosh

Campos

et al. 2019

Adv Materials Inter

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pollution. Repellent surfaces hinder liquid spreading and for that purpose, are frequently used for fluid management on open surfaces. In some cases, both repellent and adhesive domains are required for efficient fluid management. [1] Wettability engineering, i.e., the spatial modification of surface energy and morphology, is a suitable option for fluid management and has been explored extensively to deliver innovative advances in materials chemistry, fabrication techniques, and a fundamental understanding of tunable liquid properties from extreme repellency to extreme wetting. In particular, superliquid-repellent surfaces have shown great promise for self-cleaning, [2] anti-fogging, [3] anti-icing, [4] drag reduction, [5] and corrosion resistance [6] applications, among others. However, the majority of prior research has focused on applications employing high-surface-tension (γ) liquids (e.g., water, γ water ≈ 72 mN m −1 ). Difficulties arise when designing surfaces that are super-repellent to low-surface-tension liquids (20-40 mN m −1 ), where wetting interactions are more sensitive to surface chemistry and surface roughness. The methodology to making a surface repellent to these liquids is essentially the same, with surface energy and surface roughness being key factors. [7] As wetting behavior is governed by competing surface forces at the contact line, [8] liquid affinity (assuming chemical and physical attributes remain constant) is mainly dependent on the probe liquid's surface tension. Ideally, high-performing superoleophobic (extreme repellency to oils and other hydrocarbons) surfaces will exhibit Cassie-Baxter [9] type wetting across a wide range of surface-tension values. However, there may be instances where Wenzel [10] type (or complete) wetting is observed with liquids of low surface tension.In order to make surfaces with specially designed reentrant structures that promote repellency to low γ liquids, [11] researchers have typically relied on costly and complex microfabrication techniques. However, scalable, large-area, sprayable superoleophobic coatings have been explored by only a few groups. [12] In addition, an ultra-omniphobic (repellent to many liquids) material (FD-POSS; (1H,1H,2H,2H-heptadec afluorodecyl) 8 Si 8 O 12 ) has been synthesized by the Air Force Research Laboratory, and is currently considered the lowest surface-energy crystalline solid material with a solid-air surface energy of 10 mN m −1 . [13] This compound is functionalized Preparing surfaces that repel low-surface-tension liquids, such as oils and hydrocarbon fuels with surface tensions below 30 mN m −1 , poses more challenges than attaining water repellency. Oleophobic surfaces are needed when organic fluids must be contained to avoid pollutant spreading. A composite material system is presented comprised of fluorinated silica (filler), a perfluoroalkyl methacrylate copolymer (binder), and fluorinated polyhedral oligomeric silsesquioxane (additive; considered the lowest surface-energy material to date), which can be ...

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“…4(a), promising perspectives are to better understand the role of pillar-scale effects and to capture them into our dropscale model. For instance, of particular interest is the effect of pinning on wicking [31], as well as the influence of the fine details of front dynamics (including the zipping mechanism) on the macroscale front propagation dynamics [13,32,33]. We also hope that our work will stimulate more applied research aiming to improve heat transfer, self-assembly of soft structures, or deposition technologies.…”

Section: -P6mentioning

confidence: 94%

“…This is clearly beyond our scope here, and we shall limit ourselves to estimations based on the lubrication approximation. Assuming h p ≪ d, we can indeed expect K(h) ∼ h 3 p (which ignores viscous friction on the pillars compared to friction on the bottom [7,13]) and…”

mentioning

confidence: 96%

“…Remarkably, it has been shown that the symmetry of the pillar array typically controls the shape of the wetting front of the drop, which can be faceted as a square (or an octagon) when the drop is deposited on a square array of pillars, or as a hexagon on a hexagonal array [2,5,6]. Following these works, an intense more recent effort has been dedicated to analyzing how the geometrical characteristics of the texture influence the advancing front dynamics [7][8][9][10][11][12][13]. Interestingly, some peculiar "microscopic" mechanisms of contact line motion were evidenced in some of these works, such as the so-called zipping mechanism which consists in the wetting of an individual pillar of the next row by the liquid front, followed by lateral progression along this row [6,11].…”

mentioning

confidence: 99%

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Evaporation dynamics of completely wetting drops on geometrically textured surfaces

Mekhitarian¹,

Sobac²,

Dehaeck³

et al. 2017

EPL

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-This study deals with the evaporation dynamics of completely wetting and highly volatile drops deposited on geometrically textured but chemically homogeneous surfaces. The texturation consists in a cylindrical pillars array with a square pitch. The triple line dynamics and the drop shape are characterized by an interferometric method. A parametric study is realized by varying the radius and the height of the pillars (at fixed interpillar distance), allowing to distinguish three types of dynamics: i) an evaporation-dominated regime with a receding triple line; ii) a spreading-dominated regime with an initially advancing triple line; iii) a cross-over region with strong pinning effects. The overall picture is in qualitative agreement with a mathematical model showing that the selected regime mostly depends on the value of a dimensionless parameter comparing the time scales for evaporation and spreading into the substrate texture. Introduction. -Wetting and evaporation of liquid drops on solid surfaces are of prime importance for a wide range of applications, from biomedicine and operation of DNA chips to painting and design of self-cleaning and antifouling surfaces. On the other hand, the recent development of small-scale fabrication techniques enables producing surfaces with well-defined chemical and/or geometrical textures, in the micron-range or even at the nanoscale. This offers a large range of new research possibilities, aiming in particular to improve the fundamental knowledge of wetting and evaporation/condensation of liquids on textured surfaces. In turn, a very promising outcome of such improved basic understanding could be the targeted manufacturing of novel hierarchical structures with potential applications in photovoltaics, substrates for engineered cell growth or other smart materials [1].In this work, we focus on surfaces geometrically textured by an array of cylindrical pillars with controlled dimensions (typically tens of microns). Previous studies have shown how such large-scale "roughness" influences the wetting of a drop deposited on the surface [2-4] by enhancing its wettability or non-wettability (i.e., by affecting its apparent contact angle and wetting surface). These works in particular highlighted that, in partial wetting situations, a part of the liquid can invade the surface

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Dynamics of hemiwicking

Cited by 71 publications

References 19 publications

Energy Conversion Reveals Regime Transition of Imbibition in a Rough Fracture

Energy Conversion Reveals Regime Transition of Imbibition in a Rough Fracture

Fluorinated Nanocomposite Coatings for Confinement and Pumpless Transport of Low‐Surface‐Tension Liquids

Evaporation dynamics of completely wetting drops on geometrically textured surfaces

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