Hydrodynamics of air entrainment by moving contact lines

Chan, TS; Srivastava, S Sudhir; Marchand, Antonin; Andreotti, Bruno; Biferale, Luca; Toschi, Federico; Snoeijer, JH Jacco

doi:10.1063/1.4814466

Cited by 34 publications

(46 citation statements)

References 49 publications

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“…Since the contact line is receding with respect to the plate, the influence of air can be safely neglected. This is in contrast to the plunging case, which is characterized by advancing contact lines and the presence of air is crucial to the dynamic wetting transition (Marchand et al 2012;Chan et al 2013;Vandre, Carvalho & Kumar 2013). Accordingly, previous theoretical work on forced dewetting omitted the air effect and considered the problem as a single-phase flow with a free surface (Eggers 2004(Eggers , 2005Snoeijer et al 2006Snoeijer et al , 2008.…”

Section: Governing Equations and Methodologymentioning

confidence: 89%

Film deposition and transition on a partially wetting plate in dip coating

Gao

Feng

et al. 2016

J. Fluid Mech.

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We investigate the entrainment of liquid films on a partially wetting plate vertically withdrawn from a reservoir of viscous liquid using a combination of diffuseinterface numerical simulation and lubrication analysis. So far available theoretical investigations were commonly conducted by focusing on separate parameter regions, and a complete description of the flow regimes with increasing plate speed is still missing. By solving the full Stokes equations, we present a complete scenario of film transition in the presence of moving contact line. With increasing plate speed, we identify numerically four successive flow regimes in terms of the interfacial morphologies: (1) a stationary meniscus, (2) a speed-independent thick film connected to the liquid bath through a stationary dimple, (3) coexistence of a thick film and the classical Landau-Levich-Derjaguin (LLD) film connected by a propagating capillary shock and (4) a film with a monotonically varying thickness. The characteristics of the film profiles in different regions of the interfaces are analysed with lubrication theory as applicable, and satisfactory agreements with the numerical results are obtained. In particular, we confirm that the onset of film deposition occurs at a vanishing apparent contact angle, consistent with the predictions of lubrication theory. Numerical results suggest that the critical capillary number for the onset of film deposition is smaller than that for the onset of LLD film despite the fact that it is higher than the experimentally observed one, showing that the thick film can be realized in the two-dimensional model. We also demonstrated that the LLD film is triggered by the bifurcation of the stationary dimple, which is found to admit multiple branches of stable and unstable solutions.

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Section: Governing Equations and Methodologymentioning

confidence: 89%

Film deposition and transition on a partially wetting plate in dip coating

Gao

Feng

et al. 2016

J. Fluid Mech.

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“…For unfavorable case of M < 1, the invading fluid advances along the top and bottom surfaces with thin films under strong imbibition conditions ( θ ≈7 ∘ ) (Levaché & Bartolo, ), whereas it advances along the center between the top and bottom surfaces under strong drainage conditions ( θ ≈150 ∘ ) (Zhao, ; Zhao et al, ). On the other hand, for favorable case M > 1 considered in this paper, the invading fluid phase only moves along the center regardless of θ (Chan et al, ) if C a > C a ic . To obtain the critical capillary number C a ic that corresponds to the occurrence of the incomplete displacement, we solve a four‐dimensional dynamical system for the force‐balance equation that describes the meniscus shape with various C a and θ values (supporting information Figure S7).…”

Section: Phase Diagram With Corner Flowmentioning

confidence: 85%

Wettability and Flow Rate Impacts on Immiscible Displacement: A Theoretical Model

Wan

Yang

et al. 2018

Geophysical Research Letters

120

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When a more viscous fluid displaces a less viscous one in porous media, viscous pressure drop stabilizes the displacement front against capillary pressure fluctuation. For this favorable viscous ratio conditions, previous studies focused on the front instability under slow flow conditions but did not address competing effects of wettability and flow rate. Here we study how this competition controls displacement patterns. We propose a theoretical model that describes the crossover from fingering to stable flow as a function of invading fluid contact angle θ and capillary number Ca. The phase diagram predicted by the model shows that decreasing θ stabilizes the displacement for θ≥45° and the critical contact angle θc increases with Ca. The boundary between corner flow and cooperative filling for θ < 45° is also described. This work extends the classic phase diagram and has potential applications in predicting CO2 capillary trapping and manipulating wettability to enhance gas/oil displacement efficiency.

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“…A Navier-slip boundary condition is applied along the moving substrate to avoid the stress singularity caused by applying the no-slip boundary condition at the contact line (Huh & Scriven 1971;Dussan 1976;Chan et al 2013;Sibley, Nold & Kalliadasis 2015):…”

Section: Governing Equations and Boundary Conditionsmentioning

confidence: 99%

Dynamic wetting failure in surfactant solutions

et al. 2016

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The influence of insoluble surfactants on dynamic wetting failure during displacement of Newtonian fluids in a rectangular channel is studied in this work. A hydrodynamic model for steady Stokes flows of dilute surfactant solutions is developed and evaluated using three approaches: (i) a one-dimensional (1D) lubrication-type approach, (ii) a novel hybrid of a 1D description of the receding phase and a 2D description of the advancing phase, and (iii) an asymptotic theory of Cox (J. Fluid Mech., vol. 168, 1986b, pp. 195-220). Steady-state solution families in the form of macroscopic contact angles as a function of the capillary number are determined and limit points are identified. When air is the receding fluid, Marangoni stresses are found to increase the receding-phase pressure gradients near the contact line by thinning the air film without significantly changing the capillary-pressure gradients there. As a consequence, the limit points shift to lower capillary numbers and the onset of wetting failure is promoted. The model predictions are then used to interpret decades-old experimental observations concerning the influence of surfactants on air entrainment (Burley & Kennedy, Chem. Engng Sci., vol. 31, 1976, pp. 901-911). In addition to being a computationally efficient alternative for the rectangular geometries considered here, the hybrid modelling approach developed in this paper could also be applied to more complicated geometries where a thin air layer is present near a contact line.

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Hydrodynamics of air entrainment by moving contact lines

Cited by 34 publications

References 49 publications

Film deposition and transition on a partially wetting plate in dip coating

Film deposition and transition on a partially wetting plate in dip coating

Wettability and Flow Rate Impacts on Immiscible Displacement: A Theoretical Model

Dynamic wetting failure in surfactant solutions

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