Dripping dynamics and transitions at high Bond numbers

Rubio-Rubio, Mariano; Taconet, Paloma; Sevilla, A.

doi:10.1016/j.ijmultiphaseflow.2018.02.017

Cited by 23 publications

(6 citation statements)

References 26 publications

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“…Droplet formation by dripping in a gravity field has been studied in numerous works (for example, refs − ), theoretically, numerically, and experimentally. Droplet formation and ejection in centrifugal systems has been studied in refs and , and a thorough description has been proposed in ref , where a combined experimental and theoretical approach was used to describe the ejection regimes and construct a phase diagram of droplet ejection by centrifugation.…”

Section: Qualitative Description Of the Centrifugal Encapsulation Pro...mentioning

confidence: 99%

Physical Analysis of the Centrifugal Microencapsulation Process

Badalan

Ghigliotti

Achard

et al. 2022

Ind. Eng. Chem. Res.

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Centrifugal microcapsule synthesis has been shown to be a promising technique for microencapsulation, satisfying at the same time many requirements needed for biomedical applications (controlled monodisperse size, spherical shape, sterile production environment) and allowing a high capsule production rate, using only conventional lab material. Although efforts have been made over the past decade to optimize centrifugal devices, so far only one stage of the capsule synthesis process has been accurately characterized from a physical and mechanical point of view. In this work we provide the first complete description and modeling of the entire centrifugal encapsulation process, by carefully analyzing all its stages using a combined experimental and analytical approach. This results in defining novel global models and a flow diagram of the process. The analysis and models introduced here are expected to contribute to the understanding, design, improvement, and optimal operation of current and future centrifugal microencapsulation devices. Results obtained for void capsules (beads) are confirmed by experiments on capsules with cargo.

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Section: Qualitative Description Of the Centrifugal Encapsulation Pro...mentioning

confidence: 99%

Physical Analysis of the Centrifugal Microencapsulation Process

Badalan

Ghigliotti

Achard

et al. 2022

Ind. Eng. Chem. Res.

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“…The transition was shown to be delayed at low viscosities, where a buffer regime, called the complex dripping regime, occurs before the jetting regime. A later study 5 shows that the previous scaling laws do not apply for very large nozzles and proposes an alternative group of dimensionless numbers to capture flow regime transition in the limit of negligible viscous effects.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Liquid dripping from nozzles has been studied extensively in the literature − as it is observed commonly in faucets, − and also in diverse applications such as printing, − fiber coating, , microencapsulation, − and fuel injection. , The associated flows are governed by the complex interplay of surface tension, gravitational, inertial, and viscous forces. However, a slow dripping process can be described using a sequence of quasistatic shapes determined by the balance between surface tension and gravitational forces …”

Section: Introductionmentioning

confidence: 99%

Capillary-Driven Rise of Well-Wetting Liquid on the Outer Surface of Cylindrical Nozzles

et al. 2021

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Well-wetting liquids exiting small-diameter nozzles in the dripping regime can partially rise up along the outer nozzle surfaces. This is problematic for fuel injectors and other devices such as direct-contact heat and mass exchangers that incorporate arrays of nozzles to distribute liquids. We report our experimental and numerical study of the rising phenomenon for wide ranges of parameters. Our study shows that the interplay of three dimensionless numbers (the Bond number, the Weber number, and the Ohnesorge number) governs the capillary-driven rise dynamics. In general, as the flow rate or the viscosity increases, the capillary-driven rise height over each dripping period becomes smaller. We identify liquid flow rates below which the temporal evolution of the meniscus positions can be well approximated by a quasistatic model based on the Young–Laplace equation. Our analysis reveals two critical Bond numbers that give nozzle sizes, which correspond to the maximum meniscus rise and the onset of capillary-driven rise cessation. These critical Bond numbers are characterized as a function of the contact angle, regardless of the fluid type. Our study leads to a more efficient and optimized nozzle design in systems using wetting liquids by reducing both the risks of contamination and high pressure drop in such devices.

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“…The formation of identical millimeter-sized droplets in the periodic dripping mode is of interest and is important in science and applications [33][34][35][36]. In the periodic dripping regime, a liquid thread connects the top portion of the droplet, and the remainder of the liquid at the end of the tube approximates accurately a liquid cone and gradually thins.…”

Section: Introductionmentioning

confidence: 99%

“…A study of viscous liquid drop formation at the tip of a vertical tube in ambient air was conducted, where the effects of the surface tension and the tube diameter on drop and thread formation were examined [33]. Rubio-Rubio et al also reported the dripping dynamics in a wide range of liquid viscosities and injector radii and revealed the existence of dripping regimes at high Bond number [34]. Drop pinch-off at a nozzle was observed, and the neck of the drop shrank in an accelerated manner that was similar to the instability of a liquid cylinder [35].…”

Section: Introductionmentioning

confidence: 99%

An experimental study on drop formation from a capillary tube

Wang

Zhang

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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The dispersal of liquid into ambient air through a tube is a common method of identical drop formation. In the present work, the regimes and dynamics of droplet and/or jet formation during ejection from a vertical capillary nozzle are experimentally studied. The time evolutions of regimes of droplet and/or jet formation are recorded using a high-speed camera. The periodic dripping (PD), dripping faucet (DF), and jetting (J) regimes of deionized (DI) water and anhydrous ethanol are clearly observed as the Weber (We = ρV 2 D/σ) number increases. In the PD regime, drops periodically detach from the end of the capillary tube due to gravity overcoming the surface tension force. The mass of the detaching drops starts to vary from periodic to quasi-periodic in the DF regime, and a continuous jet with a smooth interface is formed in the J regime. The transition from PD to J occurs with an increase in the Weber number. The DF regime is difficult to identify and observe for anhydrous ethanol due to the lower surface tension. Over a complete period of dripping, a drop gradually changes from spherical-to pear-shaped. A liquid thread connects the top portion of the drop, and the remaining liquid at the end of tube gradually forms and pinches off over time. The period of drop emission of DI water is substantially longer than that of anhydrous ethanol for a selected tube due to the larger surface tension force. The dimensionless length Z tip /D 0 continues to gradually increase with oscillations for DI water, while initially exhibiting very slight oscillations and subsequently suddenly increasing to its maximum value for ethanol. A linear relation between the period of drop emission and number of drops is identified in the PD regime. The dimensionless length of the drops increases and the dimensionless width varies minimally as the flow rate increases. The dimensionless limiting length (or thread) depends strongly on the flow rate and the tube diameter. Meanwhile, the liquid thread that connects the top portion of the droplet to the remainder of the liquid in the tube gradually thins as the tube diameter decreases, and faster narrowing was observed.

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Dripping dynamics and transitions at high Bond numbers

Cited by 23 publications

References 26 publications

Physical Analysis of the Centrifugal Microencapsulation Process

Physical Analysis of the Centrifugal Microencapsulation Process

Capillary-Driven Rise of Well-Wetting Liquid on the Outer Surface of Cylindrical Nozzles

An experimental study on drop formation from a capillary tube

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