A consistent mass and momentum flux computation method for two phase flows. Application to atomization process

Vaudor, Geoffroy; Ménard, Thibaut; Aniszewski, Wojciech; Döring, M.; Berlemont, Alain

doi:10.1016/j.compfluid.2017.04.023

Cited by 73 publications

(80 citation statements)

References 29 publications

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“…Recently, a new method has been developed and implemented by Orazzo & al. [12] hereinafter referred as Conservative MOMentum (CMOM), inspired by [13]. The momentum equation is written in the conservative form (3a) and treated with finite volume formulation.…”

Section: Conservative Momentum (Cmom) Algorithmmentioning

confidence: 99%

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Toward direct numerical simulation of high speed droplet impact

et al. 2019

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When a liquid drop impacts a solid surface or a liquid film, several outcomes are possible. In particular, splashing phenomena can exhibit complex behaviors, like the formation of very thin crowns and emission of small droplets. Underlying mechanisms are hard to elucidate, partly due to the difficulty for current experimental devices to access to the very small length scales involved. Here, we use direct numerical simulation to explore low and high velocity drop impact phenomena. We show that classical incompressible two-phase methods can be sufficient to address low energy impacts and take into account wetting phenomena. However, dedicated robust and conservative methods are needed to simulate splashing phenomenon at higher velocities. In our test cases, we show that an impact on a thick liquid film exhibits thick crown formation and delayed splashing. On a dry wall, on the other hand, splashing phenomenon can be difficult to reproduce even with high velocity impacts. We show however how a higher value of the surrounding air density may trigger splashing. The presence of a even very thin liquid film on the wall strongly modifies impact outcome, forcing the ejection of a thin crown and subsequent secondary droplet emission.

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Section: Conservative Momentum (Cmom) Algorithmmentioning

confidence: 99%

“…This second approach is in our opinion easier to implement in a solver using LS function. LS boundary condition under the solid surface is written as stated in (13) and take into account the contact angle. The VOF condition stay unchanged, since VOF ghost cells under the wall are not needed due to its impermeability.…”

Section: Contact Angle Implementationmentioning

confidence: 99%

Toward direct numerical simulation of high speed droplet impact

et al. 2019

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“…The convective term is computed in a mass/momentum conserving framework [16,17], where one part comes from mass fluxes deduced by the VOF advection and the second part comes from a WENO5 interpolation. The diffusive term is computed thanks to the method developed by Sussman [18] and physical properties are expressed by the VOF or Level Set functions.…”

Section: Methodsmentioning

confidence: 99%

Comparison between numerical and experimental water-in-oil dispersion in a microchannel

Desjonquéres

Ménard

Tarlet

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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The dispersion of water inside a flow of oil is investigated in a microfluidic device, producing a water-in-oil emulsion. The liquid-liquid flow mainly differs from those presented in existing literature through its high capillary number (between 3 and 14), and in the head-on collision between water and oil streams. By comparing with experimental data, numerical simulations can provide more information about the topology of the flow. A coupled Volume of Fluid and Level Set method (CLSVOF) is used to treat the interface between both phases and incompressible Navier-Stokes equations are solved. Three set of parameters, close to those in the experimental setup, are investigated to compare experimental and numerical results. The comparison between experiments and simulation provides a precise knowledge of the liquid-liquid dispersion process and the overall flow pattern within the microfluidic device. KeywordsMicrochannel, water-in-oil dispersion, liquid-liquid flow Introduction Liquid-liquid dispersion within microfluidic devices has become an important issue over the last decade [1]. An emulsion is defined as the temporarily stable dispersion of a liquid into another one that is not miscible [2]. When the scale of the liquid-liquid flow is smaller than its capillary length [3], interfacial tension dominates over shear stress and gravity [4], making the dispersion highly reproducible in slow conditions [5]. These slow conditions ensure a highly monodisperse emulsion [6], that is usually appropriate for targeted applications like microreaction synthesis [7]. However, other application like high flow-rate biofuel production [8] benefit from the considerably increased surface-to-volume ratio [9,10] of microfluidic liquid-liquid dispersion. In order to better understand the physics of microfluidic in high flow-rate liquid-liquid dispersion, experimental results of the obtained mean diameter and liquid-liquid flow photographies [8] are compared to numerical results. At the present stage, a quantitative validation of the model is not obtained, but we present a qualitative comparison of the liquid-liquid flow pattern. In a first part, experimental material and methods are presented, then numerical methods used to investigate such flows are briefly detailed. Finally, first comparisons are discussed.

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“…DNS codes, such as the ARCHER code [4], may be used for simulations of academic and some simple injection configurations. The results of these simulations help to better understand the phenomena, while accurate information on detailed physics is sometimes hard to extract from experimental measurements [6,7,8,9,10]. However, configurations at large Reynolds number, that characterizes the turbulent regime of the flow, or at large Weber number, related to the stability of the interface, may be extremely costly from a numerical point of view and DNS may fail in predicting the smallest interfacial structures, like small droplets or thin ligaments.…”

Section: Introductionmentioning

confidence: 99%

Statistical modeling of the gas–liquid interface using geometrical variables: Toward a unified description of the disperse and separated phase flows

Essadki

Drui

Chaisemartin

et al. 2019

International Journal of Multiphase Flow

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In this work, we investigate an original strategy in order to derive a statistical modeling of the interface in gas-liquid two-phase flows through geometrical variables. The contribution is two-fold. First it participates in the theoretical design of a unified reducedorder model for the description of two regimes: a disperse phase in a carrier fluid and two separated phases. The first idea is to propose a statistical description of the interface relying on geometrical properties such as the mean and Gauss curvatures and define a Surface Density Function (SDF). The second main idea consists in using such a formalism in the disperse case, where a clear link is proposed between local statistics of the interface and the statistics on objects, such as the number density function in Williams-Boltzmann equation for droplets. This makes essential the use of topological invariants in geometry through the Gauss-Bonnet formula and allows to include the works conducted on sprays of spherical droplets. It yields a statistical treatment of populations of non-spherical objects such as ligaments, as long as they are homeomorphic to a sphere. Second, it provides an original angle and algorithm in order to build statistics from DNS data of interfacial flows. From the theoretical approach, we identify a kernel for the spatial averaging of geometrical quantities preserving the topological invariants. Coupled to a new algorithm for the evaluation of curvatures and surface that preserves these invariants, we analyze two sets of DNS results conducted with the ARCHER code from CORIA with and without topological changes and assess the approach.

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A consistent mass and momentum flux computation method for two phase flows. Application to atomization process

Cited by 73 publications

References 29 publications

Toward direct numerical simulation of high speed droplet impact

Toward direct numerical simulation of high speed droplet impact

Comparison between numerical and experimental water-in-oil dispersion in a microchannel

Statistical modeling of the gas–liquid interface using geometrical variables: Toward a unified description of the disperse and separated phase flows

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