Why bumpy is better: The role of the dissipation distribution in slip flow over a bubble mattress

Haase, Anja; Wood, Jeffery A.; Lammertink, Rob G.H.; Snoeijer, Jacobus Hendrikus

doi:10.1103/physrevfluids.1.054101

Cited by 23 publications

(21 citation statements)

References 15 publications

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“…Measurement of the slip length of a surface would indirectly support the present correlation of slip and scaling. Beyond scaling, the investigation of current slippery surface is useful for quantifying the flow resistance of the inner surface of a channel (Choi, Ulmanella et al 2006, Truesdell, Mammoli et al 2006, Daniello, Waterhouse et al 2009, Haase, Wood et al 2016. Low friction has been shown at a nanopatterned surface (Cottin-Bizonne, Barrat et al 2003), which might be related to the formation of "nanobubbles" that gave rise to reduced friction resulting in a slippery surface (Tyrrell andAttard 2001, Shin, Park et al 2015).…”

Section: Origin Of Anti-scaling: Hypothesismentioning

confidence: 99%

Slippery for scaling resistance in membrane distillation: A novel porous micropillared superhydrophobic surface

et al. 2019

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Scaling in membrane distillation (MD) is a key issue in desalination of concentrated saline water, where the interface property between the membrane and the feed become critical. In this paper, a new slippery mechanism was explored as an innovative concept to understand the scaling behavior in membrane distillation for a soluble salt, NaCl. The investigation was based on a novel design of a superhydrophobic polyvinylidene fluoride (PVDF) membrane with micro-pillar arrays (MP-PVDF) using a micromolding phase separation (µPS) method. The membrane showed a contact angle of 166.0 ± 2.3° and the sliding angle of 15.8 ± 3.3°. After CF4 plasma treatment, the resultant membrane (CF4-MP-PVDF) showed a reduced sliding angle of 3.0 o. In direct contact membrane distillation (DCMD), the CF4-MP-PVDF membrane illustrated excellent anti-scaling in concentrating saturated NaCl feed. Characterization of the used membranes showed that scaling due to NaCl crystals and possible membrane wetting occurred on the control PVDF and MP-PVDF membranes, but not on the CF4-MP-PVDF membrane. To understand this phenomenon, a "slippery" theory was introduced and correlated the sliding angle to the slippery surface of CF4-MP-PVDF and its anti-scaling property. This work provides a well-defined physical and theoretical platform for investigating scaling problems in membrane distillation and beyond.

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Section: Origin Of Anti-scaling: Hypothesismentioning

confidence: 99%

Slippery for scaling resistance in membrane distillation: A novel porous micropillared superhydrophobic surface

et al. 2019

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“…Ybert et al (2007) have proposed simple scaling laws for estimating the wall slip potentially obtainable from different superhydrophobic surfaces in wetting-stable conditions (Seo, García-Mayoral & Mani 2015). Studies onto wetting stability (Emami et al 2013) and drag reduction (Davies et al 2006;Haase et al 2016;Li, Alame & Mahesh 2017;Alinovi & Bottaro 2018) in the laminar regime report that the amount of drag reduction provided by a superhydrophobic surface depends on the resulting wall slip it can provide. This quantity has been found to scale approximately linearly with the texture size, as long as capillary forces are capable of robustly retain the lubricating gas layer (Lee, Choi & Kim 2016).…”

Section: State Of the Artmentioning

confidence: 99%

Laminar–turbulent transition in channel flow with superhydrophobic surfaces modelled as a partial slip wall

2019

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Superhydrophobic surfaces are capable of trapping gas pockets within the micro-roughnesses on their surfaces when submerged in a liquid, with the overall effect of lubricating the flow on top of them. These bio-inspired surfaces have proven to be capable of dramatically reducing skin friction of the overlying flow in both laminar and turbulent regimes. However, their effect in transitional conditions, in which the flow evolution strongly depends on the initial conditions, has still not been deeply investigated. In this work the influence of superhydrophobic surfaces on several scenarios of laminar–turbulent transition in channel flow is studied by means of direct numerical simulations. A single phase incompressible flow has been considered and the effect of the micro-structured superhydrophobic surfaces has been modelled imposing a slip condition with given slip length at both walls. The evolution from laminar, to transitional, to fully developed turbulent flow has been followed starting from several different initial conditions. When modal disturbances issued from linear stability analyses are used for perturbing the laminar flow, as in supercritical conditions or in the classical K-type transition scenario, superhydrophobic surfaces are able to delay or even avoid the onset of turbulence, leading to a considerable drag reduction. Whereas, when transition is triggered by non-modal mechanisms, as in the optimal or uncontrolled transition scenarios, which are currently observed in noisy environments, these surfaces are totally ineffective for controlling transition. Superhydrophobic surfaces can thus be considered effective for delaying transition only in low-noise environments, where transition is triggered mostly by modal mechanisms.

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“…There is now a large body of literature where λ is studied analytically (Philip 1972;Lauga & Stone 2003;Sbragaglia & Prosperetti 2007;Davis & Lauga 2009Crowdy 2010Crowdy , 2011bSchönecker & Hardt 2013;Crowdy 2015aCrowdy , 2016Haase et al 2016), numerically (Ng & Wang 2010;Teo & Khoo 2010;Crowdy 2015b) and experimentally (Choi et al 2003;Lee & Choi 2008;Wexler et al 2015;Nizkaya et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Slip length for longitudinal shear flow over an arbitrary-protrusion-angle bubble mattress: the small-solid-fraction singularity

Schnitzer

2017

J. Fluid Mech.

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We study the effective slip length for unidirectional flow over a superhydrophobic mattress of bubbles in the small-solid-fraction limit ǫ ≪ 1. Using scaling arguments and utilising an ideal-flow analogy we elucidate the singularity of the slip length as ǫ → 0: relative to the periodicity it scales as log(1/ǫ) for protrusion angles 0 ≤ α < π/2 and as ǫWe continue with a detailed asymptotic analysis using the method of matched asymptotic expansions, where 'inner' solutions valid close to the solid segments are matched with 'outer' solutions valid on the scale of the periodicity, where the bubbles protruding from the solid grooves appear to touch. The analysis yields asymptotic expansions for the effective slip length in each of the protrusion-angle regimes. These expansions overlap for intermediate protrusion angles, which allows us to form a uniformly valid approximation for arbitrary protrusion angles 0 ≤ α ≤ π/2. We thereby explicitly describe the transition with increasing protrusion angle from a logarithmic to an algebraic small-solid-fraction slip-length singularity.

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Why bumpy is better: The role of the dissipation distribution in slip flow over a bubble mattress

Cited by 23 publications

References 15 publications

Slippery for scaling resistance in membrane distillation: A novel porous micropillared superhydrophobic surface

Slippery for scaling resistance in membrane distillation: A novel porous micropillared superhydrophobic surface

Laminar–turbulent transition in channel flow with superhydrophobic surfaces modelled as a partial slip wall

Slip length for longitudinal shear flow over an arbitrary-protrusion-angle bubble mattress: the small-solid-fraction singularity

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