Drop Stream – Immiscible Jet Collisions:  Regimes and Fragmentation Mechanisms

Planchette, Carole; Hinterbichler, Hannes; Brenn, Günter

doi:10.4995/ilass2017.2017.4707

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…Tsuru, private discussion 2019), the possibility of manufacturing capsules (Yeo et al 2004) or more generally the use of such collisions as a method to encapsulate one liquid in the shell of another one (Planchette, Lorenceau & Brenn 2012). Recently, interest has also raised for drop-jet collisions (Planchette, Hinterbichler & Brenn 2018a;Planchette et al 2018b), which has also been called in-air microfluidics (Visser et al 2018). Such collisions typically aim -beside gaining basic knowledge on capillary-inertial systems -at producing advanced capsules or fibres by solidifying the liquid structures formed upon collisions (Kamperman et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Influence of liquid miscibility and wettability on the structures produced by drop–jet collisions

et al. 2019

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Section: Introductionmentioning

confidence: 99%

Influence of liquid miscibility and wettability on the structures produced by drop–jet collisions

et al. 2019

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“…The geometric term L j describes the distance between two consecutive impacting droplets (see figure 1(b)), which is normalized by the diameter of the jet D j . By exceeding a critical value of L j /D j , the jet breaks into a regular stream of encapsulated droplets [44,50,55,56]. The critical value of the reference case G5/SO5 is approximately 2, as indicated by the solid line in figure 2(a).…”

Section: B Liquidsmentioning

confidence: 95%

Effects of viscosity on liquid structures produced by in-air microfluidics

2020

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This study experimentally investigates the effect of viscosity on the outcomes of collisions between a regular stream of droplets and a continuous liquid jet. A broad variation of liquid viscosity of both the drop and the jet liquid is considered, keeping other material properties unchanged. To do so, only two liquid types were used: aqueous glycerol solutions for the drop and different types of silicone oil for the jet liquid. Combining these liquids, the viscosity ratio λ = µ drop /µjet was varied between 0.25 and 3.50. The collision outcomes were classified in the form of regime maps leading to four main regimes: drops-in-jet, fragmented drops-in-jet, encapsulated drops, and mixed fragmentation. We demonstrate that, depending on the drop and jet viscosity, not all four regimes can be observed in the domain probed by our experiments. The experiments reveal that the jet viscosity mainly affects the transition between drops-in-jet and encapsulated drops, which is shifted towards higher drop spacing for more viscous jets. The drop viscosity leaves the previous transition unchanged, but modifies the threshold of the drop fragmentation within the continuous jet. We develop a model that quantifies how the drop viscosity affects its extension, which is at first order fixing its shape during recoil and is therefore determining its stability against pinch-off. I. INTRODUCTIONThe large number of recent scientific publications dedicated to encapsulation shows the increasing need for reliable, precise and scalable technologies. This demand is mainly motivated by the biomedical and pharmaceutical industries, which strive to deliver actives as efficiently and safely as possible [1][2][3][4]. The development of cell culture and tissue engineering requires, beyond the necessity of cell feeding and harvesting, a mean, to manipulate and assemble the cells, which can be achieved by their regular and controlled encapsulation into a matrix [5][6][7][8]. The need of encapsulation is also rising in less demanding applications such as in the production of cosmetic, food-products, agricultural inputs, and in depollution tasks [9][10][11][12][13][14].To tackle these challenges, several methods have been proposed. For the production of well controlled spherical capsules, the technology of choice is microfluidics. Indeed, since researchers have been using this toolbox, many microdroplet based applications emerged, including chemical micro-reactors, multiple emulsions and cell capsules [15][16][17][18]. Yet, while present in the scientific community since decades, microfluidics has barely made it to industries. Beside the need for precise chips requiring appropriate design and manufacture, the risk of clogging remains, the main issue which considerably limits scale-up possibilities [19][20][21]. Regarding the production of fibers, which are especially desirable for medical and biomedical applications [22][23][24], the state of the art relies on coaxial or emulsion electrospinning. The former, however, enables only the production of core-sh...

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“…We additionally extend the concept of stretching separation to drops colliding with a continuous jet. These collisions, also called in-air microfluidics, create well-defined liquid structures (Planchette, Hinterbichler & Brenn 2017a), which can be solidified into fibres or capsules with high precision and throughput (Visser et al 2018). Yet, studies on drop-jet (D-J) collisions remain rather rare.…”

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confidence: 99%

“…Yet, studies on drop-jet (D-J) collisions remain rather rare. Chen, Chiu & Lin (2006) investigated the out-of-plane collisions of water drops with a water jet, followed by Planchette et al (2017aPlanchette et al ( , 2018, who worked with immiscible liquid pairs on in-plane collisions. In this case, the outcomes were classified according to the fragmentation of either the drops, the jet, both phases or none.…”

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Universality of stretching separation

2022

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We develop a model to predict the fragmentation limit of drops colliding off-centre. The prediction is excellent over a wide range of liquid properties and it can be used without adjusting any parameter. The so-called stretching separation is attributed to the extension of the merged drop above a critical aspect ratio of 3.25. The evolution of this aspect ratio is influenced by the liquid viscosity and can be interpreted via an energy balance. This approach is then adapted to drop–jet collisions, which we model as consecutive drop–drop collisions. The fragmentation criterion is similar to that observed for drop–drop collisions, while the evolution of the stretched jet aspect ratio is modified to account for the different flow fields and geometry.

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Drop Stream – Immiscible Jet Collisions: Regimes and Fragmentation Mechanisms

Cited by 3 publications

References 8 publications

Influence of liquid miscibility and wettability on the structures produced by drop–jet collisions

Influence of liquid miscibility and wettability on the structures produced by drop–jet collisions

Effects of viscosity on liquid structures produced by in-air microfluidics

Universality of stretching separation

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