Direct numerical simulations of gas/liquid multiphase flows

Tryggvason, Grétar; Esmaeeli, Asghar; Lu, Jiacai; Biswas, Souvik

doi:10.1016/j.fluiddyn.2005.08.006

Cited by 291 publications

(401 citation statements)

References 122 publications

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“…In the "one-fluid approach" [37] one considers a single fluid with variable viscosity and density, and a singular surface tension force, yielding the Navier-Stokes equations that read:…”

Section: Methodsmentioning

confidence: 99%

Droplet impact on a thin liquid film: anatomy of the splash

2016

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We investigate the dynamics of drop impact on a thin liquid film at short times in order to identify the mechanisms of splashing formation. Using numerical simulations and scaling analysis, we show that the splashing formation depends both on the inertial dynamics of the liquid and the cushioning of the gas. Two asymptotic regimes are identified, characterized by a new dimensionless number J: when the gas cushioning is weak, the jet is formed after a sequence of bubbles are entrapped and the jet speed is mostly selected by the Reynolds number of the impact. On the other hand, when the air cushioning is important, the lubrication of the gas beneath the drop and the liquid film controls the dynamics, leading to a single bubble entrapment and a weaker jet velocity.

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“…In the "one-fluid approach" [37] one considers a single fluid with variable viscosity and density, and a singular surface tension force, yielding the Navier-Stokes equations that read:…”

Section: Methodsmentioning

confidence: 99%

Droplet impact on a thin liquid film: anatomy of the splash

2016

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“…Popinet 40 and Popinet 41 provide a comprehensive description of this numerical technique. For a detailed review on various numerical methods in free-surface and interfacial flows, we refer the reader to Scardovelli and Zaleski 42 , Tryggvason et al 43 An initial impulse disturbance in such flows eventually develops into a nonlinear KelvinHelmholtz wave that grows and propagates downstream in a self-similar manner, see for example Hoepffner et al 44 and Orazzo and Hoepffner 45 . This flow situation is a simple configuration whereby the catapult mechanism in a planar two-phase mixing layer can be readily examined numerically.…”

Section: Vortex Shedding As a Driving Mechanism For Droplet Ejectionmentioning

confidence: 99%

Vortices catapult droplets in atomization

et al. 2013

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A droplet ejection mechanism in planar two-phase mixing layers is examined. Any disturbance on the gas-liquid interface grows into a Kelvin-Helmholtz wave and the wave crest forms a thin liquid film that flaps as the wave grows downstream. Increasing the gas speed, it is observed that the film breaks-up into droplets which are eventually thrown into the gas stream at large angles. In a flow where most of the momentum is in the horizontal direction, it is surprising to observe these large ejection angles. Our experiments and simulations show that a recirculation region grows downstream of the wave and leads to vortex shedding similar to the wake of a backward-facing step. The ejection mechanism results from the interaction between the liquid film and the vortex shedding sequence: a recirculation zone appears in the wake of the wave and a liquid film emerges from the wave crest; the recirculation region detaches into a vortex and the gas flow over the wave momentarily reattaches due to the departure of the vortex; this reattached flow pushes the liquid film down; by now, a new recirculation vortex is being created in the wake of the wave-just where the liquid film is now located; the liquid film is blown-up from below by the newly formed recirculation vortex in a manner similar to a bag-breakup event; the resulting droplets are catapulted by the recirculation vortex.

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“…the Level Set approach [25], or the VOF function resulting from the projection of a Lagrangian tracking of the interface, i.e. the Front Tracking method [26]. In these three approaches, the standard incompressible Navier-Stokes equations are considered, with an additive specific capillary source term that accounts for the normal jump of constraints at the interface.…”

Section: Introductionmentioning

confidence: 99%

A priori filtering and LES modeling of turbulent two-phase flows application to phase separation

et al. 2018

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The Large Eddy Simulation (LES) of two-phase flows with resolved scale interfaces is investigated through the a priori filtering of Direct Numerical Simulations (DNS) of one-fluid and multifield models. A phase inversion benchmark [1][2][3][4] is considered highlighting many coalescence and interface rupture events in a kind of atomization process. The order of magnitude of specific two-phase subgrid LES terms is first considered with the two modeling approaches. Then, different existing models such as Smagorinsky [5], Wall-Adapting Local Eddyviscosity (WALE) model [6], Bardina [7], Mixed [8] and Approximate Deconvolution Model (ADM) [9] are used to account for two-phase subgrid effects. These models are compared to filtered DNS results. The main conclusion concerning a priori LES filtering is that the inertia term is not predominant in two-phase flows with fragmentation and rupture of interface. This conclusion is different from that of the studies of [3,[10][11][12][13]. concerning LES models, functional modeling do 1 not correlate to filtered DNS results whereas structural approaches do. Bardina and ADM are clearly the good LES framework to consider for two-phase flows with resolved scale interfaces. ADM is clearly better than Bardina in our study. The authors greatly acknowledge the reviewer for its comments and remarks that have guided us in improving the technical and editorial aspects of the manuscript. From a general point of view, all the comments and remarks recommended by the reviewer have been taken into account. They are highlighted in the text in red. More specifically, we can detail them as follows: COMPUTERS & FLUIDS 1) I would recommend to add the main conclusions to the abstract and to add a separate section conclusions to the paper.In agreement with reviewer remark and in order to improve the fast reading and understanding of the paper, we have included a conclusion part in the abstract. In addition, the last section have been extended to "Summary, conclusion and future work", with addition of conclusions in order to highlight the originality and main results of the work. 2) Abstract : DNS and ADM should be defined.Done. The same has been achieved for the Wall-Adapting Local Eddy-viscosity (WALE) model. 3) A streak of the interface points towards the upper left corner of the box. Is that physical?Yes, this a physical feature of the interface. As we are dealing with liquid-liquid twophase flows, when the light fluid (blue surface) goes to the top part of the cavity under gravity effects, heavy liquid can be trapped near vertical walls or vertical corners, inducing this king of interface topology.4) The sentence "Among the few existing …" seems to have a grammar mistake. Detailed Response to ReviewersThis sentence has been rewritten as follows "Among the few existing references, it is worth mentioning the work on LES formulation for the one-fluid model and subsequent a priori LES filtering of DNS simulations for the estimate of new specific two-phase contributions in the mass, momentu...

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Direct numerical simulations of gas/liquid multiphase flows

Cited by 291 publications

References 122 publications

Droplet impact on a thin liquid film: anatomy of the splash

Droplet impact on a thin liquid film: anatomy of the splash

Vortices catapult droplets in atomization

A priori filtering and LES modeling of turbulent two-phase flows application to phase separation

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