Momentum and mass transport over a bubble mattress: the influence of interface geometry

Haase, Anja; Karatay, Elif; Tsai, Peichun Amy; Lammertink, Rob G.H.

doi:10.1039/c3sm51408k

Cited by 29 publications

(19 citation statements)

References 49 publications

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“…In this idealization, we have neglected an additional mechanism for a dissipation connected with the meniscus curvature [13,43,44], which may have an influence on a hydrodynamic force. Note however, that such a situation is not unrealistic, and has been achieved in many recent experiments [8,19,45].…”

Section: Model and Theoretical Estimatesmentioning

confidence: 97%

Lattice-Boltzmann simulations of the drag force on a sphere approaching a superhydrophobic striped plane

Dubov

Schmieschek

Asmolov

et al. 2014

The Journal of Chemical Physics

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By means of lattice-Boltzmann simulations the drag force on a sphere of radius R approaching a superhydrophobic striped wall has been investigated as a function of arbitrary separation h. Superhydrophobic (perfect-slip vs. no-slip) stripes are characterized by a texture period L and a fraction of the gas area φ. For very large values of h/R we recover the macroscopic formulae for a sphere moving towards a hydrophilic no-slip plane. For h/R = O(1) and the drag force is smaller than predicted by classical theories for hydrophilic no-slip surfaces, but larger than expected for a sphere interacting with a uniform perfectly slipping wall. At a thinner gap, h ≪ R the force reduction compared to a classical result becomes more pronounced, and is maximized by increasing φ. In the limit of very small separations our simulation data are in quantitative agreement with an asymptotic equation, which relates a correction to a force for superhydrophobic slip to texture parameters. In addition, we examine the flow and pressure field and observe their oscillatory character in the transverse direction in the vicinity of the wall, which reflects the influence of the heterogeneity and anisotropy of the striped texture. Finally, we investigate the lateral force on the sphere, which is detectable in case of very small separations and is maximized by stripes with φ = 0.5.

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Section: Model and Theoretical Estimatesmentioning

confidence: 97%

Lattice-Boltzmann simulations of the drag force on a sphere approaching a superhydrophobic striped plane

Dubov

Schmieschek

Asmolov

et al. 2014

The Journal of Chemical Physics

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“…9 for F s = 0.5, H = 1 μm, L p = 0.25 μm, and Re = 20. The numerical results reported by Haase et al (2013) are drawn along with the results from current simulations in Fig. 9.…”

Section: Dynamic Liquid-gas Interface Formationmentioning

confidence: 99%

“…A particular category of hydrophobic microchannels with surfaces textured with ribs and cavities has been extensively investigated by experimental Maynes et al, 2007;Byun et al, 2008;Karatay et al, 2013aKaratay et al, , 2013b, theoretical (Bazant and Vinogradova, 2008;Davis and Lauga, 2009;Teo and Khoo, 2009;Woolford et al, 2009;Belyaev and Vinogradova, 2010;Schmieschek et al, 2012), and computational (Haase et al, 2013;Wang et al, 2013;Maynes and Crockett, 2014;Teo and Khoo, 2014;Gaddam et al, 2015;Li et al, 2016) means. Important parameters which govern the slipping phenomena in these channels are hydraulic diameter, channel pressure, air diffusion, length and depth of cavity, periodicity of ridges, surface contact angle, and the liquid-gas interface geometry in particular (Haase et al, 2013;Karatay et al, 2013aKaratay et al, , 2013bTeo and Khoo, 2014). When liquid comes in contact with textures, an interface forms between the water and entrapped air which ensures a fakir-like or a Cassie-Baxter state till the air/vapor dissolves Govardhan et al, 2009;Dilip et al, 2014Dilip et al, , 2015Xue et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the numerical simulation of hydrodynamics plays a major role in the understanding of dynamics of fluid flow through stripped channels. The numerical prediction of the hydrodynamics of slipping and sticking surfaces was carried out by different numerical strategies such as molecular dynamics (Cottin-Bizonne et al, 2004), lattice Boltzmann method (Benzi et al, 2006;Harting et al, 2010), dissipative particle dynamics (Ranjith et al, 2014Ranjith, 2015), and computational fluid dynamics (Davies et al, 2006;Haase et al, 2013;Maynes and Crockett, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Numerical simulation of liquid–gas interface formation in long superhydrophobic microchannels with transverse ribs and grooves

Joseph¹,

Mathew²,

Krishnaraj³

et al. 2019

Exp. Comput. Multiph. Flow

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Superhydrophobic microchannels have evolved recently as an accepted strategy to mitigate the hydrodynamic resistance tendered in micro-constrictions. In this work, hydrodynamics of a hydrophobic microchannel realized by entrapping air in the cavities located between transversely oriented ribs is numerically investigated. An interface formed between the liquid and air/vapor in the confinement facilitates a resistance free slipping surface for the flowing water. The shape of the meniscus is determined by the pressure difference between air and liquid and is classified as convex, flat, and concave depending on the protrusion angle. Several applications require a long hydrophobic channel in which the liquid pressure decreases lengthwise; consequently the interface shape changes as well. In this regard, a mathematical model is proposed to predict the protrusion angle at a specific distance from the inlet of microchannel. This is incorporated in the computational fluid dynamics (CFD) simulations to define the static geometry of the interface which is varying throughout the length of the channel. Moreover, the boundary is treated as a combination of flat no-slip and curved shear-free regions to mimic the ribs and cavities. Further, the evolution of interface morphology is captured using the volume-of-fluid (VOF) scheme by considering a static contact angle at the solid surface to check the validity of the suggested model. Dynamically evolved protrusion angle is measured for various liquid-gas interface pressures and it is observed that the theoretical scaling proposed by Laplace and Young is well obeyed. Though CFD-VOF simulation scheme is an effective tool for predicting the pressure dependent liquid-gas meniscus and concurrent hydrodynamics of the ribbed microchannel, it is resource intensive. The present study demonstrates that the developed model for static boundary may be adopted alternatively to predict the hydrodynamics of a long hydrophobic microchannel by saving computational resources. Keywordshydrophobic microchannel ribbed channel volume-of-fluid simulation liquid-gas interface

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“…In such a description, we neglect an additional mechanism for a dissipation connected with the meniscus curvature [15,38,39]. Note however that such an ideal situation has been achieved in many recent experiments [40][41][42]. The origin of coordinates is placed at the flat interface, characterized by a slip length b(y), spatially varying in one direction, and the texture varies over a period L.…”

Section: Model and Governing Equationsmentioning

confidence: 99%

Effective slippage on superhydrophobic trapezoidal grooves

Zhou

Asmolov

Schmid

et al. 2013

The Journal of Chemical Physics

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We study the effective slippage on superhydrophobic grooves with trapezoidal cross-sections of various geometries (including the limiting cases of triangles and rectangular stripes), by using two complementary approaches. First, dissipative particle dynamics (DPD) simulations of a flow past such surfaces have been performed to validate an expression [E. S. Asmolov and O. I. Vinogradova, J. Fluid Mech. 706, 108 (2012)] that relates the eigenvalues of the effective slip-length tensor for one-dimensional textures. Second, we propose theoretical estimates for the effective slip length and calculate it numerically by solving the Stokes equation based on a collocation method. The comparison between the two approaches shows that they are in excellent agreement. Our results demonstrate that the effective slippage depends strongly on the area-averaged slip, the amplitude of the roughness, and on the fraction of solid in contact with the liquid. To interpret these results, we analyze flow singularities near slipping heterogeneities, and demonstrate that they inhibit the effective slip and enhance the anisotropy of the flow. Finally, we propose some guidelines to design optimal one-dimensional superhydrophobic surfaces, motivated by potential applications in microfluidics.

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Momentum and mass transport over a bubble mattress: the influence of interface geometry

Abstract: COMSOL models and data files belonging to the publication: A.S. Haase, E. Karatay, P.A. Tsai, R.G.H. Lammertink, Momentum and mass transport over a bubble mattress: the influence of interface geometry. Soft Matter 9, 8949–8957 (2013)

Cited by 29 publications

References 49 publications

Lattice-Boltzmann simulations of the drag force on a sphere approaching a superhydrophobic striped plane

Lattice-Boltzmann simulations of the drag force on a sphere approaching a superhydrophobic striped plane

Numerical simulation of liquid–gas interface formation in long superhydrophobic microchannels with transverse ribs and grooves

Effective slippage on superhydrophobic trapezoidal grooves

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