Droplet tilings for rapid exploration of spatially constrained many-body systems

Molina, Anton; Kumar, Shailabh; Karpitschka, Stefan; Prakash, Manu

doi:10.1073/pnas.2020014118

Cited by 10 publications

(15 citation statements)

References 47 publications

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“…In situations involving an even larger number of volatile oil droplets, the data are consistent in showing that these droplets fail to coalesce. Their rich patterns of collective translational mobility, which qualitatively resemble behavior already known for organic droplets on aqueous surfactant solutions ( 27 – 29 , 38 – 40 ), are beyond the scope of this study.…”

Section: Resultsmentioning

confidence: 86%

Oil-on-water droplets faceted and stabilized by vortex halos in the subphase

Pahlavan

Chen

et al. 2023

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

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For almost 200 y, the dominant approach to understand oil-on-water droplet shape and stability has been the thermodynamic expectation of minimized energy, yet parallel literature shows the prominence of Marangoni flow, an adaptive gradient of interfacial tension that produces convection rolls in the water. Our experiments, scaling arguments, and linear stability analysis show that the resulting Marangoni-driven high-Reynolds-number flow in shallow water overcomes radial symmetry of droplet shape otherwise enforced by the Laplace pressure. As a consequence, oil-on-water droplets are sheared to become polygons with distinct edges and corners. Moreover, subphase flows beneath individual droplets can inhibit the coalescence of adjacent droplets, leading to rich many-body dynamics that makes them look alive. The phenomenon of a “vortex halo” in the liquid subphase emerges as a hidden variable.

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Section: Resultsmentioning

confidence: 86%

Oil-on-water droplets faceted and stabilized by vortex halos in the subphase

Pahlavan

Chen

et al. 2023

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

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“…(2020) and Molina et al. (2021). Another strong advantage is that, because of its gradient dynamics form, the presented mesoscopic model may readily serve as a building block in mesoscopic descriptions of more complex systems.…”

Section: Discussionmentioning

confidence: 95%

“…for the modelling of the collective evaporation dynamics of random ensembles and regular arrays of drops as recently studied, e.g. by Carrier et al (2016), Hatte et al (2019b), Pandey et al (2020), Chong et al (2020) and Molina et al (2021). Another strong advantage is that, because of its gradient dynamics form, the presented mesoscopic model may readily serve as a building block in mesoscopic descriptions of more complex systems.…”

Section: Discussionmentioning

confidence: 99%

Sessile drop evaporation in a gap – crossover between diffusion-limited and phase transition-limited regime

et al. 2023

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We consider the time evolution of a sessile drop of volatile partially wetting liquid on a rigid solid substrate. The drop evaporates under strong confinement, namely, it sits on one of the two parallel plates that form a narrow gap. First, we develop an efficient mesoscopic long-wave description in gradient dynamics form. It couples the diffusive dynamics of the vertically averaged vapour density in the narrow gap to an evolution equation for the profile of the volatile drop. The underlying free energy functional incorporates wetting, interface and bulk energies of the liquid and gas entropy. The model allows us to investigate the transition between diffusion-limited and phase transition-limited evaporation for shallow droplets. Its gradient dynamics character allows for a long-wave as well as a full-curvature formulation. Second, we compare results obtained with the mesoscopic long-wave model to corresponding direct numerical simulations solving the Stokes equation for the drop coupled to the diffusion equation for the vapour as well as to selected experiments. In passing, we discuss the influence of contact line pinning.

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“…S1 and Table S1 ). In the one-phase region, due to solutal Marangoni flows, the droplet maintains a quasi-stationary, contracted state with a nonzero apparent contact angle θ app and a high mobility, i.e., an unpinned contact line ( 25 – 28 ) ( Fig. 1 A ).…”

mentioning

confidence: 99%

How liquid–liquid phase separation induces active spreading

Chao

Ramìrez-Soto

Bahr

et al. 2022

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

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The interplay between phase separation and wetting of multicomponent mixtures is ubiquitous in nature and technology and recently gained significant attention across scientific disciplines, due to the discovery of biomolecular condensates. It is well understood that sessile droplets, undergoing phase separation in a static wetting configuration, exhibit microdroplet nucleation at their contact lines, forming an oil ring during later stages. However, very little is known about the dynamic counterpart, when phase separation occurs in a nonequilibrium wetting configuration, i.e., spreading droplets. Here we show that liquid–liquid phase separation strongly couples to the spreading motion of three-phase contact lines. Thus, the classical Cox–Voinov law is not applicable anymore, because phase separation adds an active spreading force beyond the capillary driving. Intriguingly, we observe that spreading starts well before any visible nucleation of microdroplets in the main droplet. Using high-speed ellipsometry, we further demonstrate that the evaporation-induced enrichment, together with surface forces, causes an even earlier nucleation in the wetting precursor film around the droplet, initiating the observed wetting transition. We expect our findings to improve the fundamental understanding of phase separation processes that involve dynamical contact lines and/or surface forces, with implications in a wide range of applications, from oil recovery or inkjet printing to material synthesis and biomolecular condensates.

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Droplet tilings for rapid exploration of spatially constrained many-body systems

Cited by 10 publications

References 47 publications

Oil-on-water droplets faceted and stabilized by vortex halos in the subphase

Oil-on-water droplets faceted and stabilized by vortex halos in the subphase

Sessile drop evaporation in a gap – crossover between diffusion-limited and phase transition-limited regime

How liquid–liquid phase separation induces active spreading

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