Interaction between two deforming liquid drops in tandem and various off-axis arrangements subject to uniform flow

Kékesi, T.; Altimira, Mireia; Amberg, Gustav; Wittberg, Lisa Prahl

doi:10.1016/j.ijmultiphaseflow.2018.11.009

Cited by 10 publications

(8 citation statements)

References 45 publications

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“…Turning now to the isolated droplet, it experiences the well-known multi-bag breakup regime, in which the droplet gradually deforms into a disk-like shape followed by the creation of a bag at its periphery (not shown here). In addition, its breakup occurs much slower compared to the cluster arrangement, at approximately t/tsh=2.3 compared to t/tsh=1.4 (and 1.2 in the 3-D simulation); this observation was also reported in the work of [6]. Regarding the comparison between the 2-D and 3-D simulations, they both predict similar droplet shapes up to t/tsh=0.8, while after t/tsh=1 a deviation is observed.…”

Section: Comparison Between the Computational Domainssupporting

confidence: 77%

“…(2) The aerodynamic breakup of isolated droplets has been thoroughly investigated (see for example [2] among many others); more recently the breakup of droplets in tandem formations has been also reported [4][5][6]. On the other hand, not much focus has been paid to the breakup of droplets moving in parallel with respect to the surrounding air; such collective droplet cluster motions can be considered more representative for the conditions typically realised in fuel sprays consisting of a large number of droplets [1].…”

Section: Introductionmentioning

confidence: 99%

“…It was found that for the parallel arrangement, the droplets experience higher drag force compared to the isolated droplet and also a weak attraction. Recently, Kekesi et al [6] studied numerically using the VOF method the breakup of two liquid droplets arranged at various positions from tandem up to parallel, with We=20, Re=20 and 50, and L/D0 and H/D0 ranging from 1.5 up to 5. Three scenarios were identified for the breakup of the droplets: i) they collide and merge, ii) the secondary drop shoot through the primary drop and iii) the two drops behave independently.…”

Section: Introductionmentioning

confidence: 99%

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Numerical investigation of the aerodynamic breakup of a parallel moving droplet cluster

Stefanitsis

Strotos

Νikolopoulos

et al. 2019

International Journal of Multiphase Flow

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The present work examines numerically the aerodynamic breakup of a cluster of Diesel droplets moving in parallel with respect to the gas flow. Two-and three-dimensional simulations of the incompressible Navier-Stokes equations together with the VOF method are performed for Weber (We) numbers in the range of 5 up to 60 and non-dimensional distance between the droplets (H/D0) ranging from 1.25 to 20. The numerical results indicate that the proximity of droplets affects their breakup for distances H/D0≤5. For low droplet proximity distances (H/D0≤2.5), the droplets experience the socalled shuttlecock breakup mode, which has been also identified for droplets in tandem formations in a previous authors' work and is characterized by an oblique peripheral stretching of the droplet. With decreasing H/D0 the breakup initiation time decreases, while the drag coefficient increases relative to that of isolated droplets. When the distance between the droplets is low enough (H/D0<1.5), this can result in critical We number, i.e. minimum We number leading to breakup, lower than that of an isolated droplet at the same conditions.

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Section: Comparison Between the Computational Domainssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical investigation of the aerodynamic breakup of a parallel moving droplet cluster

Stefanitsis

Strotos

Νikolopoulos

et al. 2019

International Journal of Multiphase Flow

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“…Nevertheless, at low Reynolds numbers the axisymmetric approximation has proven to be relatively accurate during deformation stages [51,55,56]. In addition, in [57,58] some 3D simulations show that symmetry is present in the low Reynolds regime. Finally, the axisymmetric simulations do not allow the prediction of the characteristics of the secondary droplets resulting from the breakup of the main droplet, which is not the aim of the current work.…”

Section: Computational Setup and Examined Conditionsmentioning

confidence: 99%

Numerical investigation of the aerodynamic breakup of droplets in tandem

Stefanitsis

Malgarinos

Strotos

et al. 2019

International Journal of Multiphase Flow

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights Numerical examination of the aerodynamic breakup of four Diesel droplets in tandem formation at representative engine conditions. Identification of a new breakup mode in the multi-mode regime, termed as "shuttlecock". Droplet proximity becomes important for non-dimensional distances between the droplets lower than 9. Drag coefficient and liquid surface area of the "representative chain droplet" are lower than the corresponding ones of the isolated droplet; breakup initiation time is longer and the critical We number is higher. Proposed correlations to predict the drag coefficient, liquid surface area, breakup initiation time and critical We of the "representative chain droplet".

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“…At the initial time of calculation, the two droplets were spheric with the same diameter, D. The inlet was the velocity boundary, and the ou pressure boundary. Based on our previous study [16] and the simulations conducted by K [14,15] and Jiao et al [10], a scheme of six levels was used to locally refine the c region-the grid size of the inner computation region was halved when a new added. The maximum length of the grid was D and the minimum grid length as shown in Figure 3.…”

Section: Geometry Setup and Meshmentioning

confidence: 99%

Interactions between Two Deformable Droplets in Tandem Fixed in a Gas Flow Field of a Gas Well

et al. 2021

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Knowing the droplet-deformation conditions, the droplet-breakup conditions, and the drag force in the interaction between two droplets with a high Reynolds number is of importance for tracking droplet movement in the annular flow field of a gas well. The interactions between two droplets with a high Reynolds number in a tandem arrangement fixed in flowing gas was investigated. The volume of fluid (VOF) method was used to model the droplets’ surface structure. Two different body forces were exerted on both droplets to hold them suspended at a fixed location, which eliminated the effect of droplet acceleration or deceleration on the drag and decreased the amount of computation required. The exerted body forces were calculated using the Newton iteration procedure. The interactions between the two droplets were analyzed by comparison with the simulation results of a single isolated droplet. The effect of the separation distance on the drag force was investigated by changing the separation spacing. The simulation results showed that for droplets with a small separating space between them, the dynamics of the downstream droplet were influenced significantly by the upstream droplet. The drag coefficient of the downstream droplet decreased considerably to a small, even negative, value, especially for droplets with higher Weber numbers and smaller initial separating spaces between them, while the drag force of the upstream droplet was influenced only slightly. In addition, a formula for predicting the final drag coefficient of the downstream droplet was devised.

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Interaction between two deforming liquid drops in tandem and various off-axis arrangements subject to uniform flow

Cited by 10 publications

References 45 publications

Numerical investigation of the aerodynamic breakup of a parallel moving droplet cluster

Numerical investigation of the aerodynamic breakup of a parallel moving droplet cluster

Numerical investigation of the aerodynamic breakup of droplets in tandem

Interactions between Two Deformable Droplets in Tandem Fixed in a Gas Flow Field of a Gas Well

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