Three-dimensional flow computation for two interacting, moving droplets

Kim, I.; Elghobashi, S.; Sirignano, William A.

doi:10.2514/6.1992-343

Cited by 6 publications

(6 citation statements)

References 7 publications

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“…The results of the ratio ̅̅̅̅̅̅̅̅ / ̅̅̅̅̅̅ are shown in Figure 10 as a function of We and L/D 0 as calculated by the CFD simulations (colored circles) along with the predictions of equation (3) (iso-lines), with c 1 = 0.038, c 2 = 1.1 and c 3 = 0.53. The ratio ̅̅̅̅̅̅̅̅ / ̅̅̅̅̅̅ decreases when the ratio L/D 0 is decreasing, in agreement with previous studies [28][29][30][31][32][33], reaching values down to 0.75. A strong dependence of the ratio on the We number is observed as depicted by the iso-lines, something that is attributed to the dependence of the frontal area on the We number as well.…”

Section: Drag Coefficientsupporting

confidence: 92%

“…Regarding the numerical modelling of droplet chains, Kim et al [28][29][30] studied the flow over two solid and liquid spheres using a three-dimensional implicit finite-difference algorithm for Re numbers ranging from 50 up to 150 and non-dimensional distances from 1.5 up to 25. They examined the flow structure and drag coefficient, and observed that the latter becomes almost identical to that of the isolated droplet for L/D 0 >9.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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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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Section: Drag Coefficientsupporting

confidence: 92%

Section: Accepted Manuscriptmentioning

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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“…The ratio Cd,cl/Cd,is increases with decreasing H/D0, reaching values as high as 29 for the first approach and 15 for the second one. This trend is in agreement with the works of [1,15,[17][18][19]. Overall, the drag coefficient of droplets in cluster formations differs from that of the isolated droplet for distances H/D0≤3 for the first method, and H/D0≤2 for the second.…”

Section: Drag Coefficientsupporting

confidence: 92%

“…This breakup mode is encountered for H/D0≤2. Numerical simulations with droplets and solid spheres were performed by Kim and coworkers in [17,18] for Re=100 and H/D0 ranging from 1.5 up to 25. They found that for H/D0<9 the drag coefficient of the droplets is higher than that of an isolated droplet at the same conditions.…”

Section: Introductionmentioning

confidence: 99%

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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“…For the conservation of mass and momentum, the governing equations for incompressible, viscous, and immiscible two-phase flows are described as follows [19][20][21]:…”

Section: Governing Equationsmentioning

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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Three-dimensional flow computation for two interacting, moving droplets

Cited by 6 publications

References 7 publications

Numerical investigation of the aerodynamic breakup of droplets in tandem

Numerical investigation of the aerodynamic breakup of droplets in tandem

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

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

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