Transient stresses of two-dimensional model droplet emulsions subjected to simple shear flow by numerical simulations

Kim, See Jo; Hwang, Wook Ryol

doi:10.1007/s13367-011-0020-8

Cited by 3 publications

(2 citation statements)

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“…[10][11][12] For droplets generating systems controlled by external ows, many works have been conducted on the droplets breakup mechanism during generation stage. [13][14][15][16][17] However, the stability of compound droplets during storage (or solidifying) stage will be the key factor to yield polymer microspheres. To ensure the stability of double emulsions, introducing hydrophobic surfactants at the interface of W1/O internal emulsion and hydrophilic surfactants for the external interface of the oil globules attract a great deal of attention.…”

Section: Introductionmentioning

confidence: 99%

Influence of sucrose on the stability of W1/O/W2 double emulsion droplets

Lin

Liu

et al. 2015

RSC Adv.

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Large sized W1/O/W2 double emulsion droplets with uniform wall thickness and diameters were prepared by adopting the emulsion microencapsulation method. Via visually online counting the number of double emulsion droplets over observing time, the stability of these compound droplets solidified in a constant rotating flow field was comprehensively studied. Combining emulsion kinetics, the adsorption radius of polymer chains, surface tension and rheological properties of the outer water phase (W2), the influence of sucrose concentration on the stability of double emulsion droplets was systematically investigated.Combining the change of surface tension, the size of adsorbed polyvinyl alcohol (PVA) chains and storage modulus of the W2 phase, mechanisms of the interactions between sucrose molecules and PVA chains were fully elucidated in this paper. Moreover, the results showed that the stability of the double emulsion droplets was improved when the contents of sucrose was less than 1.0 wt%. This is probably due to the proper match between shear force and surface tension of the W2 phase, and less inward force caused by osmotic pressure in dilute sucrose concentrations. 0816 2493148; Tel: +86 0816 2490194 † Electronic supplementary information (ESI) available: Fig. S1 shows density (r) of W2 phase with various sucrose concentrations. Fig. S2(a) shows schematic diagram of behavior of PVA dissolved in water: the outer part of the circle is air, the dark blue ring is concentrated PVA solution, and the center part is dilute PVA solution, Fig. S2(b) displays schematic diagram of interaction between PVA chains and sucrose molecules. Fig. S3 presents osmotic pressure of W2 phase with various sucrose concentrations. See

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Section: Introductionmentioning

confidence: 99%

Influence of sucrose on the stability of W1/O/W2 double emulsion droplets

Lin

Liu

et al. 2015

RSC Adv.

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“…This author is unaware of any thorough evaluation of this method against theoretical and empirical models. Kim and Hwang [44] show the method is able to reproduce a variety of droplet systems, with varying viscosity ratios and capillary numbers. The accuracy of the results is only explored so-far as to say that the trends in viscosity agree with the models of Taylor [6] and Pal [45].…”

Section: Meso-scale Modelsmentioning

confidence: 99%

Development of explicit and constitutive lattice-Boltzmann models for food product rheology

Burgin¹

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Emulsions are found throughout various industries including oil extraction, biological materials, and food products such as milk, condiments, and spreads. The study of their rheology is therefore important due to its impact on manufacturing efficiency and end product desirability. A key rheological measure is the emulsion viscosity, the fluid's resistance to flow, which affects the power required in production as well as the taste and texture. An emulsion's viscosity displays complex behaviour due to the droplet interfaces and interactions. Similarly, the sheared self-diffusion coefficient measures the amount of movement the droplets exhibit, due to the interactions between droplets. The presented mesoscopic lattice-Boltzmann models allow for these macroscopic properties to emerge from the simulations due to the explicit modelling of the droplets. A continuous surface force is applied to the lattice fluids to model droplet interfaces. The model is implemented in such a way as to allow the simulation of hundreds of droplets with limited computing power. The model is initially applied to a pipe flow, with the development of a pressure boundary condition. Boundary effects from the solid walls require their removal, using Lees-Edwards boundary conditions to represent bulk flow in a sheared system. The boundary conditions are extended to the multi-component flow, which allowed simulations to provide results for various emulsion systems with varying droplet concentrations, surface tensions, viscosity ratios, and shear rates. Trends and results from experimental and theoretical literature are recovered and constitutive models of emulsion viscosity have been evaluated. The agreement of these two dimensional lattice-Boltzmann models with three dimensional experimental results shows the usefulness of the method. The structure of the droplets and clustering behaviour they exhibit are examined and compared to solid particle suspension literature. Finally, the model is used in exploratory simulations to examine the effect of droplet bidispersity on the macroscopic properties; the witnessed effect agrees well with solid suspension literature. This mesoscopic model will allow for phenomenon on this scale to be more easily studied and may provide more accurate information for multi-scale analysis.

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