Electro-osmotic flow along superhydrophobic surfaces with embedded electrodes

Schönecker, Clarissa; Hardt, Steffen

doi:10.1103/physreve.89.063005

Cited by 9 publications

(6 citation statements)

References 31 publications

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“…It has been suggested that superhydrophobic surfaces can be employed as a means for pumping liquid in conjunction with thermocapillary flow due to a temperature gradient along the gas–liquid interface (Baier, Steffes & Hardt 2010), diffusioosmotic flow (Huang et al. 2008) or electroosmotic flow (Squires 2008; Belyaev & Vinogradova 2011; Steffes, Baier & Hardt 2011; Schönecker & Hardt 2014). It should be interesting to extend the results of the present paper to such situations in order to study the impact of surfactants in these cases.…”

Section: Discussionmentioning

confidence: 99%

Influence of insoluble surfactants on shear flow over a surface in Cassie state at large Péclet numbers

Baier

Hardt

2020

J. Fluid Mech.

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Section: Discussionmentioning

confidence: 99%

Influence of insoluble surfactants on shear flow over a surface in Cassie state at large Péclet numbers

Baier

Hardt

2020

J. Fluid Mech.

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“…The application of the reciprocal theorem (2.16) to a number of problems involving the motion of particles in low Reynolds number flows has been reviewed by Leal (1980); for several more recent applications, see Stone & Samuel (1996), Masoud & Stone (2014) and Schönecker & Hardt (2014). Its use in the present study is inspired by the works of Brenner (1964) and Stone & Samuel (1996).…”

Section: Introductionmentioning

confidence: 92%

“…where Σ comprises the particle surface Σ p (outer normal vector n = −e r ) and the surface Σ ∞ at infinity (outer normal vector n = e r ). The Lorentz theorem (3.2) has been exploited in a number of cases, for instance by Stone & Samuel (1996), Masoud &Stone (2014), andSchönecker &. Its use in the present study is inspired by the argumentation of Stone & Samuel (1996).…”

Section: Applying the Lorentz Reciprocity Theoremmentioning

confidence: 99%

Drag and diffusion coefficients of a spherical particle attached to a fluid–fluid interface

et al. 2016

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Explicit analytical expressions for the drag and diffusion coefficients of a spherical particle attached to the flat interface between two immiscible fluids are constructed for the case of a vanishing viscosity ratio between the fluid phases. The model is designed to account explicitly for the dependence on the contact angle between the two fluids and the solid surface. The Lorentz reciprocal theorem is applied in the context of geometric perturbations from the limiting cases of 90 • and 180 • contact angles. The model agrees well with the experimental and numerical data from the literature. Also, an advantage of the method utilized is that the drag and diffusion coefficients can be calculated up to one order higher in the perturbation parameter than the known velocity and pressure fields. Extensions to other particle shapes with known velocity and pressure fields are straightforward.

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“…The hydrodynamic slip length of the hydrophobic surface is an intrinsic hypothetical parameter that refers to the length below the wall where the fluid velocity extrapolates to zero . It is important to note that the synthesized engineered surface coated with hydrophobic octadecyltrichlorosilane possesses hydrophobicity and for such surfaces, a large slip length of the order of micrometer can be achieved. , The impact of the hydrodynamic slippage on the EOF has been studied by several researchers. − However, all of the previously listed investigations are conducted by considering the background electrolyte Newtonian in nature. It is noteworthy to mention that numerous biomicrofluidic applications involve fluidic media like bioliquids (e.g., blood, DNA, protein solutions), polymeric solutions, worm-like micellar solutions, colloidal suspensions, and others.…”

Section: Introductionmentioning

confidence: 99%

Electroosmotic Flow Modulation and Enhanced Mixing through a Soft Nanochannel with Patterned Wall Charge and Hydrodynamic Slippage

Pal,

Mahapatra,

Ohshima

et al. 2024

Ind. Eng. Chem. Res.

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The present study deals with the modulation of electroosmotic flow (EOF) through a soft nanochannel filled with a non-Newtonian fluid. The supporting charged hydrophobic walls of the channel are physicochemically patterned, which in turn leads to possibilities of modulated interfacial slip and surface ζ-potential. In addition, the supporting walls are grafted with an ion-and fluid-penetrable polyelectrolyte layer (PEL), which further entraps ionizable functional groups that give rise to immobile volumetric charges across the PEL. The fluid flow across such engineered devices under an applied electric field gives rise to an intricate electrohydrodynamic coupling over small scales. The mathematical model that describes the modulation of EOF across such a soft nanochannel comprises the Poisson equation for electrostatic potential and Nernst−Planck equations for conservation of the mass of mobile electrolyte ions, the flow field within the PEL is governed by a modified Darcy−Brinkman equation, and the Cauchy momentum equation governs the fluid flow outside the PEL. We adopt a radial basis function (RBF)based meshless computation scheme to simulate the set of governing equations. We further deduced analytical expressions for the electrostatic potential and velocity field for a Newtonian electrolyte through a bare channel with patterned surface potential, valid for a low charge limit. The numerical results are, however, obtained for a wide range of pertinent parameters and are further validated with the deduced theoretical results and available mathematical and experimental results from the literature. We observe an array of counter-rotating vortices that form in the flow field of the background non-Newtonian power-law fluid. Such vortices originate due to spatially periodic variations of hydrodynamic slippage as well as surface ζ-potential. The strength of vortices further intensifies due to the presence of the PEL grafted along the supporting rigid walls. The flow modulation across such a channel is illustrated by considering all of the possible sets of pertinent parameters. We further studied the impact of the rotational flow profile on the mixing of injected uncharged solutes. We observed that the formation of vortices in the flow field across the engineered soft nanochannel significantly affects the mixing efficiency, which can further be enhanced by suitably regulating the physicochemical and hydrodynamic parameters that control the flow modulation across the channel.

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Electro-osmotic flow along superhydrophobic surfaces with embedded electrodes

Cited by 9 publications

References 31 publications

Influence of insoluble surfactants on shear flow over a surface in Cassie state at large Péclet numbers

Influence of insoluble surfactants on shear flow over a surface in Cassie state at large Péclet numbers

Drag and diffusion coefficients of a spherical particle attached to a fluid–fluid interface

Electroosmotic Flow Modulation and Enhanced Mixing through a Soft Nanochannel with Patterned Wall Charge and Hydrodynamic Slippage

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