A modified phase-field method for the investigation of wetting transitions of droplets on patterned surfaces

Pashos, George; Kokkoris, George; Boudouvis, Andreas G.

doi:10.1016/j.jcp.2014.11.045

Cited by 25 publications

(24 citation statements)

References 45 publications

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“…Let us focus on the 3D post geometries. In agreement with previous studies, the wetting transition for both the short and tall posts is observed to take place via the depinning mechanism, in which the interface depins from the top of the post before sliding to the base of the system [23,32,37,[65][66][67][68][69]. This is illustrated in Fig.…”

Section: Transition Mechansisms In Three Dimensionssupporting

confidence: 91%

“…Thus, although the geometry affected the shape of the interface late in the transition, it had little bearing close to the transition state. In contrast to this, a diffuse interface model of a droplet atop a single pillar suggested that the transition was dominated by cavity condensation (which in turn is highly geometry -dependent) [37], although this formalisation was unable to track the transition.…”

Section: Introductionmentioning

confidence: 91%

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The impact of surface geometry, cavitation, and condensation on wetting transitions: posts and reentrant structures

Panter

Kusumaatmaja

2017

J. Phys.: Condens. Matter

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The fundamental impacts of surface geometry on the stability of wetting states, and the transitions between them are elucidated for square posts and reentrant structures in three dimensions. We identify three principal outcomes of particular importance for future surface design of liquid-repellent surfaces. Firstly, we demonstrate and quantify how capillary condensation and vapour cavitation affect wetting state stabilities. At high contact angles, cavitation is enhanced about wide, closely-spaced square posts, leading to the existence of suspended states without an associated collapsed state. At low contact angles, narrow reentrant pillars suppress condensation and enable the suspension of even highly wetting liquids. Secondly, two distinct collapse mechanisms are observed for 3D reentrant geometries, base contact and pillar contact, which are operative at different pillar heights. As well as morphological differences in the interface of the penetrating liquid, each mechanism is affected differently by changes in the contact angle with the solid. Finally, for highly-wetting liquids, condensates are shown to critically modify the transition pathways in both the base contact and pillar contact modes.

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Section: Transition Mechansisms In Three Dimensionssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 91%

The impact of surface geometry, cavitation, and condensation on wetting transitions: posts and reentrant structures

Panter

Kusumaatmaja

2017

J. Phys.: Condens. Matter

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“…By studying the initial spreading behavior of a droplet on highly composite -hierarchically and/or chemically patterned -solid surfaces, we concluded that there exists an inertial regime where the contact radius evolution is independent of the underlying solid substrate With nature as starting point (systems with self-cleaning properties such as lotus leafs 62 , highly adhesive rose petals 63 or even desert lizards with the ability to transport water over their skin 64 ), many researchers have focused on studying the wetting behavior of droplets on roughened substrates and then designing structure geometries to obtain desirable wetting properties 65,66 . Active control of the wetting dynamics (e.g.…”

Section: Discussionmentioning

confidence: 99%

Droplet spreading on rough surfaces: Tackling the contact line boundary condition

et al. 2016

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The complicated dynamics of the contact line of a moving droplet on a solid substrate often hamper the efficient modeling of microfluidic systems. In particular, the selection of the effective boundary conditions, specifying the contact line motion, is a controversial issue since the microscopic physics that gives rise to this displacement is still unknown. Here, a sharp interface, continuum-level, novel modeling approach, accounting for liquid/solid micro-scale interactions assembled in a disjoining pressure term, is presented. By following a unified conception (the model applies both to the liquid/solid and the liquid/ambient interfaces), the friction forces at the contact line, arXiv:1601.06540v1 [cond-mat.soft]

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“…The critical diameter required for jumping over the substrate was seen to be inversely proportional to the number of merged drops. Pashos et al (2015) proposed a modified phase-field method to find the equilibrium wetting states of a droplet-pillar system with three immiscible phases and an axisymmetric pillar. Nam et al (2015) numerically studied drop coalescence on a water-repellent surface.…”

Section: Nomenclaturementioning

confidence: 99%

Recoil of Drops During Coalescence on Superhydrophobic Surfaces

Gunjan

Somwanshi

Agrawal

et al. 2015

Interfac Phenom Heat Transfer

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A numerical and experimental study has been carried out with a pair of water drops coalescing over a superhydrophobic surface. Initially, a stationary isolated drop (of given radius R1) in the sessile configuration is just touched by another drop (of radius R2), vertically in line with it, at zero speed. The solid substrate is a chemically treated, polished superhydrophobic surface made up of copper, for which the equilibrium contact angle for water was measured to be 150 •. The Bond number, considering the total volume of the combined drop, falls in the range of 0.3-0.5. For these conditions, experiments clearly reveal that for a given range of R1/R2, the merged drop bounces off once before it starts to eventually spread and attain an equilibrium configuration. The above experiment has been numerically simulated using COMSOL c ⃝ , in an axisymmetric coordinate system. The simulations have been carried out for different combinations of droplet volumes, while keeping their combined volume to be fixed. The predictions of the simulation are compared with the experiment in terms of the interface shapes attained, distinctive timescales, and recoil height. The comparison between the two sets of data is seen to be favorable. Factors leading to recoil are delineated according to the available energy budget.

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A modified phase-field method for the investigation of wetting transitions of droplets on patterned surfaces

Cited by 25 publications

References 45 publications

The impact of surface geometry, cavitation, and condensation on wetting transitions: posts and reentrant structures

The impact of surface geometry, cavitation, and condensation on wetting transitions: posts and reentrant structures

Droplet spreading on rough surfaces: Tackling the contact line boundary condition

Recoil of Drops During Coalescence on Superhydrophobic Surfaces

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