Numerical studies of the influence of the dynamic contact angle on a droplet impacting on a dry surface

Yokoi, Kensuke; Vadillo, Damien; Hinch, E. J.; Hutchings, I.M.

doi:10.1063/1.3158468

Cited by 273 publications

(166 citation statements)

References 58 publications

(102 reference statements)

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“…However, modeling flows with moving contact lines, particularly in 3D, is very challenging. In addition to the computational resource issue associated with capturing 3D time-dependent flow, the crucial difficulty with most simulation methods, for example, the popular volume-of-fluid (VOF) approach, is that the dynamic contact angle needs to be prescribed, often in a complicated fashion [30][31][32][33], dependent on experimental measurements. Simulations of flows such as the impact and spreading of droplets are particularly sensitive to the dynamic contact angle behavior.…”

Section: Simulation Methodsmentioning

confidence: 99%

“…Simulations of flows such as the impact and spreading of droplets are particularly sensitive to the dynamic contact angle behavior. Yokoi et al [33] found that accurate dynamics could be achieved only when using a dynamic contact angle based on experimental observations. In contrast, the lattice Boltzmann method used here does not require the dynamic contact angle to be specified.…”

Section: Simulation Methodsmentioning

confidence: 99%

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Mixing and internal dynamics of droplets impacting and coalescing on a solid surface

et al. 2013

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The coalescence and mixing of a sessile and an impacting liquid droplet on a solid surface are studied experimentally and numerically in terms of lateral separation and droplet speed. Two droplet generators are used to produce differently colored droplets. Two high-speed imaging systems are used to investigate the impact and coalescence of the droplets in color from a side view with a simultaneous gray-scale view from below. Millimeter-sized droplets were used with dynamical conditions, based on the Reynolds and Weber numbers, relevant to microfluidics and commercial inkjet printing. Experimental measurements of advancing and receding static contact angles are used to calibrate a contact angle hysteresis model within a lattice Boltzmann framework, which is shown to capture the observed dynamics qualitatively and the final droplet configuration quantitatively. Our results show that no detectable mixing occurs during impact and coalescence of similar-sized droplets, but when the sessile droplet is sufficiently larger than the impacting droplet vortex ring generation can be observed. Finally we show how a gradient of wettability on the substrate can potentially enhance mixing.

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Section: Simulation Methodsmentioning

confidence: 99%

Section: Simulation Methodsmentioning

confidence: 99%

Mixing and internal dynamics of droplets impacting and coalescing on a solid surface

et al. 2013

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“…For the transport of the interface, we give here some examples showing that almost all the classical methods are concerned: Boundary Integral methods [1][2][3], adaptive grid methods [4,5], Level-Set methods [6,7], Volume of Fluid methods [8][9][10], Front Tracking Methods [11,12] and coupled Level set and Volume-of-Fluid (CLSVOF) methods [13]. Different methods have also been developed for the modeling of moving contact lines.…”

Section: Introductionmentioning

confidence: 99%

“…In recent developments, the dynamic or apparent contact angle is connected to the velocity of the contact line. The Cox [16] relation is directly applied [10,17] or adapted using an adjustable parameter that needs to be empirically determined from experiments [13,14]. As shown in this introduction, different strategies have been developed for the simulation of moving contact line.…”

Section: Introductionmentioning

confidence: 99%

Comparison between numerical models for the simulation of moving contact lines

Legendre

Maglio

2015

Computers & Fluids

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. a b s t r a c tThe aim of this study is to discus different numerically models for the simulation of moving contact lines in the context of a Volume of Fluid-Continuum Surface Force (VoF-CSF) method. We focus on the particular situation of spreading drops. We first present the numerical methods used for the simulation of moving contact line i.e. static contact angle versus dynamic contact angle, no slip condition versus slip condition. A grid and time convergence is performed for the different models. We show that the integration of the Continuum Surface Force using the finite volume method results in a grid dependence at the onset of the spreading. The static and dynamic models are compared to experiments. It is shown that the dynamic models based on the Cox's relation for the dynamic contact angle are able to reproduce experiments while static models overestimate the spreading time and are not able to reproduce the Tanner regime. The difference between static and dynamic models is shown to increase with the Ohnesorge number.

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“…A better method would be to use a more sophisticated relationship between capillary number and contact angle than the one used here. Options include those such as formulated by [24] or [25]. However, these require more detailed measurements of the dynamic contact angle at a range of capillary numbers.…”

Section: Case With No Air Co-flowmentioning

confidence: 99%

Coupled Level-Set Volume of Fluid Simulations of Water Flowing Over a Simplified Drainage Channel With and Without Air Coflow

Dianat¹,

Skarysz²,

Hodgson³

et al. 2017

SAE Int. J. Passeng. Cars - Mech. Syst.

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INTRODUCTIONPredicting and controlling the motion of rainwater over the exterior of road vehicles, EWM, is an important consideration for vehicle designers. Phenomena such as A-pillar overflow can obscure a driver's vision and droplets or rivulets falling on passengers or their belongings can be a significant source of customer dissatisfaction.There are a wide range of engineering applications involving the flow of liquid films, rivulets and droplets over solid surfaces. For example, water or ice on an airplane wing can significantly interfere with its overall performance [1,2]. Rivulets are also observed in coating flows in the chemical industry [3]. In the automotive sector examples of EWM simulations can be found in [4] and [5] that both use Lagrangian particle tracking for the airborne droplets and a simple 2D film model for the surface flow. While the approach to the dispersed phase (airborne) may be satisfactory, the assumption that the surface flow can be modelled using a 2D film has limitations. These 2D film models, details of which can be found in [6] for example, solve transport equations for the film thickness but make no attempt to resolve the 3D shape of the surface water. Using such film methods behaviour such as film-stripping and breakup can only be modelled empirically, with the results being valid within certain flow regimes. More fundamentally the two-way interaction between the aerodynamic drag on the water and the shape of the water feature cannot be predicted using such methods.The objective here is to develop and demonstrate a computational method that can capture the underlying physics and predict the motion of various liquid flow features on the exterior surface of vehicles. By predicting the resolved 3D shape of the droplet it is hoped that this will be more general than existing thin film models. By resolving water features fully in 3D it is possible to predict droplet breakup or coalescence without the need for empirical modelling as is the case for film models. ABSTRACTThe motivation for this paper is to predict the flow of water over exterior surfaces of road vehicles. We present simulations of liquid flows on solid surfaces under the influence of gravity with and without the addition of aerodynamic forces on the liquid. This is done using an implementation of a Coupled Level Set Volume of Fluid method (CLSVOF) multiphase approach implemented in the open source OpenFOAM CFD code. This is a high fidelity interface-resolving method that solves for the velocity field in both phases without restrictions on the flow regime. In the current paper the suitability of the approach to Exterior Water Management (EWM) is demonstrated using the representative test cases of a continuous liquid rivulet flowing along an inclined surface with a channel located downstream perpendicular to the oncoming flow. Experimental work has been carried out to record the motion of the rivulet in this case and also to measure the contact angle of the liquid with the solid surface. The measurements of the liquid/...

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Numerical studies of the influence of the dynamic contact angle on a droplet impacting on a dry surface

Cited by 273 publications

References 58 publications

Mixing and internal dynamics of droplets impacting and coalescing on a solid surface

Mixing and internal dynamics of droplets impacting and coalescing on a solid surface

Comparison between numerical models for the simulation of moving contact lines

Coupled Level-Set Volume of Fluid Simulations of Water Flowing Over a Simplified Drainage Channel With and Without Air Coflow

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