Role of surface charge on boundary slip in fluid flow

Pan, Yunlu; Bhushan, Bharat

doi:10.1016/j.jcis.2012.10.043

Cited by 38 publications

(54 citation statements)

References 17 publications

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“…However, because the top of OTS layer has already been negatively charged, there will be a large impact on the charge of the OTS surface. Thus, the electrostatic force with applied negative voltage to the substrate does not change [94]. …”

Section: Reviewmentioning

confidence: 99%

“…Schematic of the explanation for the results of electrostatic force measurement with positive voltage to the substrate, reproduced with permission from [94]. Copyright (2013) Elsevier.…”

Section: Reviewmentioning

confidence: 99%

“…26. With negative voltage to the substrate, the plots are almost superposed with each other, which means the slip length remained constant with different negative voltage to the substrate [94]. …”

Section: Reviewmentioning

confidence: 99%

“…With applied positive voltage, the surface charge density may have a similar trend as that in DI water, but the change should be small. The equipment may not able to measure the small change of the small electrostatic force [94]. …”

Section: Reviewmentioning

confidence: 99%

See 3 more Smart Citations

The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

Pan¹,

Bhushan²,

Zhao³

2014

Beilstein J. Nanotechnol.

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SummaryThe drag of fluid flow at the solid–liquid interface in the micro/nanoscale is an important issue in micro/nanofluidic systems. Drag depends on the surface wetting, nanobubbles, surface charge and boundary slip. Some researchers have focused on the relationship between these interface properties. In this review, the influence of an applied voltage on the surface wettability, nanobubbles, surface charge density and slip length are discussed. The contact angle (CA) and contact angle hysteresis (CAH) of a droplet of deionized (DI) water on a hydrophobic polystyrene (PS) surface were measured with applied direct current (DC) and alternating current (AC) voltages. The nanobubbles in DI water and three kinds of saline solution on a PS surface were imaged when a voltage was applied. The influence of the surface charge density on the nanobubbles was analyzed. Then the slip length and the electrostatic force on the probe were measured on an octadecyltrichlorosilane (OTS) surface with applied voltage. The influence of the surface charge on the boundary slip and drag of fluid flow has been discussed. Finally, the influence of the applied voltage on the surface wetting, nanobubbles, surface charge, boundary slip and the drag of liquid flow are summarized. With a smaller surface charge density which could be achieved by applying a voltage on the surface, larger and fewer nanobubbles, a larger slip length and a smaller drag of liquid flow could be found.

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Section: Reviewmentioning

confidence: 99%

“…Schematic of the explanation for the results of electrostatic force measurement with positive voltage to the substrate, reproduced with permission from [94]. Copyright (2013) Elsevier.…”

Section: Reviewmentioning

confidence: 99%

Section: Reviewmentioning

confidence: 99%

Section: Reviewmentioning

confidence: 99%

See 2 more Smart Citations

The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

Pan¹,

Bhushan²,

Zhao³

2014

Beilstein J. Nanotechnol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…1). All the typical length scales (particle radius, wall pattern length, and particle-wall gap) considered here are on the order of micrometers, sufficiently large to describe the fluid as a continuum obeying the Navier-Stokes equations [8,9,10,11,12] with no slippage at the solid wall [13,14,15,16,17,18,19]. Our model corresponds to the real case of sufficiently deep grooves where it can be safely assumed perfect-slip at the liquid-gas interface, see e.g.…”

Section: Introductionmentioning

confidence: 99%

Mobility tensor of a sphere moving on a superhydrophobic wall: application to particle separation

Pimponi

Chinappi

Gualtieri

et al. 2013

Microfluid Nanofluid

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The paper addresses the hydrodynamic behavior of a sphere close to a micro-patterned superhydrophobic surface described in terms of alternated no-slip and perfect-slip stripes. Physically, the perfect-slip stripes model the parallel grooves where a large gas cushion forms between fluid and solid wall, giving rise to slippage at the gas-liquid interface. The potential of the boundary element method (BEM) in dealing with mixed no-slip/perfect-slip boundary conditions is exploited to systematically calculate the mobility tensor for different particle-to-wall relative positions and for different particle radii. The particle hydrodynamics is characterized by a non trivial mobility field which presents a distinct near wall behavior where the wall patterning directly affects the particle motion. In the far field, the effects of the wall pattern can be accurately represented via an effective description in terms of a homogeneous wall with a suitably defined apparent slippage. The trajectory of the sphere under the action of an external force is also described in some detail. A "resonant" regime is found when the frequency of the transversal component of the force matches a characteristic crossing frequency imposed by the wall pattern. It is found that, under resonance, the particle undergoes a mean transversal drift. Since the resonance condition depends on the particle radius the effect can in principle be used to conceive devices for particle sorting based on superhydrophobic surfaces.

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On gel electrophoresis of dielectric charged particles with hydrophobic surface: A combined theoretical and numerical study

et al. 2017

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A theoretical study on the gel electrophoresis of a charged particle incorporating the effects of dielectric polarization and surface hydrophobicity at the particle-liquid interface is made. A simplified model based on the weak applied field and low charge density assumption is also presented and compared with the full numerical model for a nonpolarizable particle to elucidate the nonlinear effects such as double layer polarization and relaxation as well as surface conduction. The main motivation of this study is to analyze the electrophoresis of the surface functionalized nanoparticle with tunable hydrophobicity or charged fluid drop in gel medium by considering the electrokinetic effects and hydrodynamic interactions between the particle and the gel medium. An effective medium approach, in which the transport in the electrolyte-saturated hydrogel medium is governed by the Brinkman equation, is adopted in the present analysis. The governing electrokinetic equations based on the conservation principles are solved numerically. The Navier-slip boundary condition along with the continuity condition of dielectric displacement are imposed on the surface of the hydrophobic polarizable particle. The impact of the slip length on the electrophoresis is profound for a thinner Debye layer, however, surface conduction effect also becomes significant for a hydrophobic particle. Impact of hydrophobicity and relaxation effects are higher for a larger particle. Dielectric polarization creates a reduction in its electrophoretic propulsion and has negligible impact at the thinner Debye length as well as lower gel screening length.

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Role of surface charge on boundary slip in fluid flow

Cited by 38 publications

References 17 publications

The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

Mobility tensor of a sphere moving on a superhydrophobic wall: application to particle separation

On gel electrophoresis of dielectric charged particles with hydrophobic surface: A combined theoretical and numerical study

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