Effect of a surface tension gradient on the slip flow along a superhydrophobic air-water interface

  title={Effect of a surface tension gradient on the slip flow along a superhydrophobic air-water interface},
  author={Dong Song and Baowei Song and Hai-bao Hu and XiaoSong Du and Peng Du and Chang‐Hwan Choi and Jonathan P. Rothstein},
  journal={arXiv: Fluid Dynamics},
Superhydrophobic surfaces have been shown to produce significant drag reduction in both laminar and turbulent flows by introducing an apparent slip velocity along an air-water interface trapped within the surface roughness. In the experiments presented within this study, we demonstrate the existence of a surface tension gradient associated with the resultant Marangoni flow along an air-water interface that causes the slip velocity and slip length to be significantly reduced. In this study, the… 

Figures from this paper

Prediction of resistance induced by surface complexity in lubricating layers: Application to superhydrophobic surfaces

Super Hydrophobic (SH) coatings are widely used to mitigate drag in various applications. Numerous studies have demonstrated that the beneficial wall-slip effect produced by these materials

A theory for the slip and drag of superhydrophobic surfaces with surfactant

A theory for steady, pressure-driven, laminar, two-dimensional flow in a periodic SHS channel with soluble surfactant is proposed, which significantly improves predictions relative to a surfactants-free one and can provide the boundary condition in other simulations without having to solve the full problem.

Shear flow over a surface containing a groove covered by an incompressible surfactant phase

Abstract We study shear-driven liquid flow over a planar surface with an embedded gas-filled groove, with the gas–liquid interface protruding slightly above or below the planar surface. The flow

Linear instability of lid- and pressure-driven flows in channels textured with longitudinal superhydrophobic grooves

Abstract It is known that an increased flow rate can be achieved in channel flows when smooth walls are replaced by superhydrophobic surfaces. This reduces friction and increases the flux for a given

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

Abstract Surfactants can immobilize fluid–liquid interfaces under shear stress. We investigate the impact of insoluble surfactants on shear flow along a superhydrophobic surface in Cassie state, with

Three-dimensional backflow at liquid–gas interface induced by surfactant

Abstract A liquid–gas interface (LGI) on submerged microstructure surfaces has the potential to achieve large slip velocities, which is significant for underwater applications such as drag reduction.

Microgroove geometry dictates slippery hydrodynamics on superhydrophobic substrates

We report the detailed hydrodynamics over micro-grooved substrates in a confined hydrophobic microfluidic environment. In sharp contrast to the traditional premises, the liquid-air interface shape or

Effects of slowly varying meniscus curvature on internal flows in the Cassie state

The flow rate of a pressure-driven liquid through a microchannel may be enhanced by texturing its no-slip boundaries with grooves aligned with the flow. In such cases, the grooves may contain vapour

Slip of submerged two-dimensional liquid-infused surfaces in the presence of surfactants

Using numerical simulations, we investigate the effects of Marangoni stresses on the effective slip length of liquid-infused surfaces (LIS) with transverse grooves. The surfactants are assumed

Laminar drag reduction in surfactant-contaminated superhydrophobic channels

While superhydrophobic surfaces (SHSs) show promise for drag reduction applications, their performance can be compromised by traces of surfactant, which generate Marangoni stresses that increase



A numerical study of the effects of superhydrophobic surface on skin-friction drag in turbulent channel flow

Superhydrophobic surfaces have attracted much attention lately as they present the possibility of achieving a substantial skin-friction drag reduction in turbulent flows. In this paper, the effects

Direct velocity measurements of the flow past drag-reducing ultrahydrophobic surfaces

A series of experiments are presented which study the flow kinematics of water past drag-reducing superhydrophobic surfaces. The ultrahydrophobic surfaces are fabricated from silicon wafers using

Drag reduction in turbulent flows over superhydrophobic surfaces

In this paper, we demonstrate that periodic, micropatterned superhydrophobic surfaces, previously noted for their ability to provide laminar flow drag reduction, are capable of reducing drag in the

Effective slip in pressure-driven Stokes flow

Nano-bubbles have recently been observed experimentally on smooth hydrophobic surfaces; cracks on a surface can likewise be the site of bubbles when partially wetting fluids are used. Because these

Influence of slip on the flow past superhydrophobic circular cylinders

Superhydrophobic surfaces have been shown to produce significant drag reduction for both laminar and turbulent flows of water through large- and small-scale channels. In this paper, a series of

Viscoelastic Drag Forces and Crossover from No-Slip to Slip Boundary Conditions for Flow near Air-Water Interfaces.

It is shown that vibrating a small sphere mounted on an atomic force microscope cantilever near a gas bubble immersed in water is an excellent probe of surface contamination.

Slip flow past a gas–liquid interface with embedded solid particles

We simulate shear flow past a stationary monolayer of spherical particles embedded in a flat gas–liquid interface. This problem is relevant to the understanding of the microhydrodynamics of

Role of mixed boundaries on flow in open capillary channels with curved air-water interfaces.

It is found that partial slip, rather than the commonly used stress-free condition, provided a more accurate description of the boundary condition at the confined air-water interface, reflecting the key role that surface/interface effects play in controlling flow behavior on the nanoscale and microscale.

Significant and stable drag reduction with air rings confined by alternated superhydrophobic and hydrophilic strips

It is demonstrated for the first time that a large surface energy barrier can be formed to strongly pin the three-phase contact line of air/water/solid by covering the inner rotor of a Taylor-Couette flow apparatus with alternating superhydrophobic and hydrophilic circumferential strips.