Surface structure determines dynamic wetting

Wang, Jiayu; Do-Quang, Minh; Cannon, James; Feng, Yue; Suzuki, Yuji; Amberg, Gustav; Shiomi, Junichiro

doi:10.1038/srep08474

Cited by 62 publications

(56 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Shifts are easily measured using frequency scans, much as with traditional spectrometers (e.g., IR and UV). In our case, instead of probing molecular or atomistic modes, we probe droplet vibratory modes using line drag as a metric for dynamical wettability (32)(33)(34)(35). With the great proliferation of "designer supports"--chemically and mechanically conditioned surfaces tailored for desired properties (36)--there is a growing need to characterize dynamical wetting.…”

Section: Dynamic Wettability Spectrometermentioning

confidence: 99%

Droplet motions fill a periodic table

Steen

Chang

Bostwick

2019

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Drawing parallels to the symmetry breaking of atomic orbitals used to explain the periodic table of chemical elements; here we introduce a periodic table of droplet motions, also based on symmetry breaking but guided by a recent droplet spectral theory. By this theory, higher droplet mode shapes are discovered and a wettability spectrometer is invented. Motions of a partially wetting liquid on a support have natural mode shapes, motions ordered by kinetic energy into the periodic table, each table characteristic of the spherical-cap drop volume and material parameters. For water on a support having a contact angle of about 60°, the first 35 predicted elements of the periodic table are discovered. Periodic tables are related one to another through symmetry breaking into a two-parameter family tree. droplet vibrations | sessile drop dynamics | meniscus motions | capillary ballistics | moving contact line D roplets and droplet motions surround us. Our harvests depend on rain drops. We sweat, we shower, and we drink. Our eyes make tears and our blood splats. Drops enable the protein content of our bodily fluids to be measured (1), our silicon chips to be fabricated (2), and complex parts to be additively sculpted by drop-on-demand processing (3,4). Water droplets in motion are shaped into objects of beauty by surface tension. Their images have become symbols of purity and cleanliness, selling beer, jewelry, clothing, and automobiles. However, despite more than a century of study, the motions of droplets on a support have resisted systematic classification. This paper introduces the periodic table classification of capillary-ballistic droplet motions.The capillary-ballistic model assumes an ideal fluid with surface tension acting on the deformable surface (SI Appendix). Capillary-ballistic motions are typical of thin liquids like water. Prototypical of dynamics of this kind are free drop vibrations, predicted by Rayleigh to have frequencies (5) λ kl as inwhere the corresponding deformation is Y l k ðθ, φÞ in spherical coordinates. Here, wavenumber k is the degree and l is the order of the spherical harmonic Y l k (6). Frequencies [1] and mode shapes Y l k constitute the so-called Rayleigh spectrum, predictions verified experimentally (7,8). Note that, in [1], different l′s share the same frequency. These degeneracies arise from the perfect symmetry of the spherical free drop. The introduction of a support typically breaks these degeneracies.Deformations of the supported drop (9), Fig. 1 (Bottom Row), break from the Y l k ðθ, φÞ shapes. The number of layers n (Top Row, in schematic) and of sectors l [Bottom Row: bold lines, rendered shape (Right)] characterize modal symmetry. Using k = l + 2ðn − 1Þ, symmetries are alternatively classified "mathematically" by wavenumber pairs ½k, l. Modes are either "symmetric" (short for axisymmetric), e.g., [6,0]leftmost, "star," e.g., [6,6]rightmost, or "layer" modes (short for layer sector), e.g., [6,2] and ½6,4middle two modes. Note that the Rayleigh spectrum [1] splits. That is, [...

show abstract

Section: Dynamic Wettability Spectrometermentioning

confidence: 99%

Droplet motions fill a periodic table

Steen

Chang

Bostwick

2019

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…The magnified SEM image of TiO 2 nanofibers coated mesh (Figure 1d) indicates that the TiO 2 nanofibers coated stainless steel mesh has both micro and nanoscale surface roughness which is more important for manipulating the advance surface wettability. This type of micro/nano surface structure of the modified stainless steel mesh is more favorable to attract water and repel oil underwater which exhibits underwater superoleophobicity as a result of high surface roughness properties of these micro/nano surface structures (Wang et al, 2015).…”

Section: Resultsmentioning

confidence: 99%

Efficient removal of oil from oil contaminated water by superhydrophilic and underwater superoleophobic nano/micro structured TiO2 nanofibers coated mesh

Gunatilake

Bandara

2017

Chemosphere

View full text Add to dashboard Cite

In this report, we investigated the TiO nanofibers coated stainless steel mesh as a novel underwater superoleophobic membrane for the effective separation of contaminated oil-water mixtures. The membrane was fabricated by spray deposition of hydrothermally synthesized TiO nanofibers on stainless steel mesh. The fabricated membrane exhibits superhydrophilicity and supereleophobicity properties in air and underwater respectively allowing the separation of oil-water efficiently. Randomly deposited TiO nanofibers on mesh exhibit rough surface property and hence superhydrophilic nature. Water oil separation efficiencies of ∼90 and ∼99% were achieved with this filter for less viscous and highly viscous oil respectively. Additionally, the TiO nanofibers coated mesh can degrade immiscible organic molecules due to photocatalytic activity of TiO nanofibers under UV light. As a result of self-cleaning property of TiO nanofibers coated mesh, the durability of the filter membrane is enhanced.

show abstract

“…In this case, the fluid-fluid interface gets continually deformed until snap-off happens and the reversible energy, stored in the deformed interface, is lost as viscous dissipation. Recently, Wang et al (2015) described how a contact line friction parameter, derived from the model of de Gennes et al (2003), can be adjusted to fit wetting dynamics of a drop on a surface with defined roughness.…”

Section: Influence Of Microscopic Surface Heterogeneity On Two-phasementioning

confidence: 99%

A Two-Phase SPH Model for Dynamic Contact Angles Including Fluid–Solid Interactions at the Contact Line

2018

View full text Add to dashboard Cite

The description of wetting phenomena on the continuum scale is a challenging problem, since intermolecular interactions, like van der Waals forces between liquid and solid, alter the flow field at the contact line. Recently, these effects were included in the smoothed particle hydrodynamics method by introducing a contact line force (CLF) on the continuum scale. This physically based contact line force model is employed here to simulate two-phase flow in a wide range of wetting dynamics parametrized by capillary number. In particular, dynamic contact angles at various capillary number values are calculated by CLF model and compared to measured values. We find that there is significant disagreement between simulated and measured results, specially at low wetting speeds. It is indeed expected that most of the driving force is dissipated to overcome strong liquid-solid interactions, which are not adequately accounted for in the existing CLF model. Therefore, we have extended that model to account for stick-slip (SSL) behavior of the contact line caused by solid-fluid interactions. The new SSL model results in dynamic contact angle values that are in good agreement with experimental data for the full range of wetting dynamics. Keywords Dynamic contact angle • Contact line force • Two-phase flow • Stick-slip behavior • Smoothed particle hydrodynamics (SPH) List of symbols A Arbitrary field variable B Transition function for continuous surface force at solid boundary c Color function B P. Kunz

show abstract

Surface structure determines dynamic wetting

Cited by 62 publications

References 37 publications

Droplet motions fill a periodic table

Droplet motions fill a periodic table

Efficient removal of oil from oil contaminated water by superhydrophilic and underwater superoleophobic nano/micro structured TiO2 nanofibers coated mesh

A Two-Phase SPH Model for Dynamic Contact Angles Including Fluid–Solid Interactions at the Contact Line

Contact Info

Product

Resources

About