Effect of viscosity ratio on the shear-driven failure of liquid-infused surfaces

Liu, Ying; Wexler, Jason; Schönecker, Clarissa; Stone, Howard A.

doi:10.1103/physrevfluids.1.074003

Cited by 82 publications

(88 citation statements)

References 23 publications

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“…The above phenomenological mechanism suggests that, taking the lubricant viscosity as a design parameter, the intermediate viscosity ratios (e.g.μ 2 /μ 1 = 0.01 ∼ 1 depending on the specific condition) are to be avoided in the application of LIS. This is consistent with previous experiments of longitudinal grooves towards the lower viscosity branch [16]; more viscous lubricants, on the other hand, seem to ensure higher robustness.…”

Section: B Effective Slip Above the Cavitiessupporting

confidence: 93%

Effective slip over partially filled microcavities and its possible failure

Holmgren

Kronbichler

et al. 2018

Phys. Rev. Fluids

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Motivated by the emerging applications of liquid-infused surfaces (LIS), we study the drag reduction and robustness of transverse flows over two-dimensional microcavities partially filled with an oily lubricant. Using separate simulations at different scales, characteristic contact line velocities at the fluid-solid intersection are first extracted from nano-scale phase field simulations and then applied to micron-scale two-phase flows, thus introducing a multiscale numerical framework to model the interface displacement and deformation within the cavities. As we explore the various effects of the lubricant-to-outer-fluid viscosity ratioμ 2 /μ 1 , the capillary number Ca, the static contact angle θ s , and the filling fraction of the cavity δ, we find that the effective slip is most sensitive to the parameter δ. The effects ofμ 2 /μ 1 and θ s are generally intertwined, but weakened if δ < 1. Moreover, for an initial filling fraction δ = 0.94, our results show that the effective slip is nearly independent of the capillary number, when it is small. Further increasing Ca to about 0.01μ 1 /μ 2 , we identify a possible failure mode, associated with lubricants draining from the LIS, forμ 2 /μ 1 0.1. Very viscous lubricants (e.g.μ 2 /μ 1 > 1), on the other hand, are immune to such failure due to their generally larger contact line velocity.

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Section: B Effective Slip Above the Cavitiessupporting

confidence: 93%

Effective slip over partially filled microcavities and its possible failure

Holmgren

Kronbichler

et al. 2018

Phys. Rev. Fluids

View full text Add to dashboard Cite

show abstract

“…However, there are several geometrical systems that are periodic in two directions [12][13][14][15][16][17][18][19]. The challenge in extending our approach to such systems arises from the effect of wetting dynamics since the interface can now progress in two directions and interface speed is required to predict relative movement between the two directions.…”

Section: Resultsmentioning

confidence: 99%

“…Such isolation of aqueous environment is achieved by introducing an artificial defect on the surface such as an obstacle or a depression [7][8][9][10][11]. Similarly, extensive research on liquid-infused surfaces demonstrates that a trapped liquid layer over a patterned surface lends remarkable surface properties [12][13][14][15][16][17][18][19]. Thus depending on the application, it may be desirable to either remove or trap a liquid layer over a surface.…”

Section: Introductionmentioning

confidence: 99%

“…There have been a series of studies on liquid-infused surfaces with geometric features on the order ∼10 μm where the authors show how the preexisting layer of oil in a groove (a model for a liquid-infused surface) can be drained by injecting water [16][17][18][19]. They also examined the effect of aspect ratio of the groove, presence of obstacles, viscosity ratio of the two phases, and presence of surfactant in the aqueous phase on the oil drainage.…”

Section: Introductionmentioning

confidence: 99%

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Controlled liquid entrapment over patterned sidewalls in confined geometries

2017

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Liquid entrapment over patterned surfaces has applications in diagnostics, oil recovery, and printing processes. Here we study the process of oil displacement upon sequential injection of water over a photopatterned structure in a confined geometry. By varying the amplitude and frequency of triangular and sinusoidal patterns, we are able to completely remove oil or trap oil in varying amounts. We present a theoretical model based on geometrical arguments that successfully predicts the criterion for liquid entrapment and provides insights into the parameters that govern the physical process.

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“…In both cases, if the impregnated region of a surface is longer than the retainable length, the liquid that is above or upstream of the stable region will drain. In the case of LIS with longitudinal grooves, an analytical expression for the persistence length is obtained by considering both the shear stress and the external pressure gradient [94]. It shows that a higher shear stress or external pressure gradient results in lower lubricant retention and, for a given external fluid and a fixed shear stress, the less viscous lubricants achieve higher retention.…”

Section: Applications Of Weak Pinning Lismentioning

confidence: 99%

Drop mobility on chemically heterogeneous and lubricant-impregnated surfaces

Mistura

2017

Advances in Physics: X

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Controlling the motion of liquid drops in contact with a solid surface has broad technological implications in many different areas ranging from textiles to microfluidics and heat exchangers. The wettability of a surface is determined by specifying the apparent contact angle and contact angle hysteresis (CAH) that depend on the surface chemistry and morphology. The presence of chemical inhomogeneity and morphological disorder usually increases CAH. A liquid substrate, whose surface is atomically flat and homogenous, is then expected to exhibit a very low CAH. Low CAH determines high drop mobility, while high CAH favours drop pinning. Very slippery surfaces with exceptional omniphobicity are obtained by impregnating a textured solid with a lubricant. To guide and control the motion of drops, the solid surface can be decorated with suitable chemical patterns. In this review, we briefly outline the main results obtained in the past few years to passively control drop motion and produce robust omniphobic surfaces, highlighting some of the most promising applications of these novel functional surfaces.

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Effect of viscosity ratio on the shear-driven failure of liquid-infused surfaces

Cited by 82 publications

References 23 publications

Effective slip over partially filled microcavities and its possible failure

Effective slip over partially filled microcavities and its possible failure

Controlled liquid entrapment over patterned sidewalls in confined geometries

Drop mobility on chemically heterogeneous and lubricant-impregnated surfaces

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