Droplet breakup in concentrated emulsions

Jansen, K.M.B.; Agterof, W.G.M.; Mellema, J.

doi:10.1122/1.1333001

Cited by 115 publications

(68 citation statements)

References 9 publications

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“…In support of this view, the resemblance of the flow curves in Figure 7 to those in the emulsions showing droplet break up modelled by Jansen et al [35] is striking. …”

Section: Emulsions Inspection Of the T-t G Values Insupporting

confidence: 73%

Low shear rheological behaviour of two-phase mesophase pitch

Ramjee

Rand

Focke

2015

Carbon

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“…In support of this view, the resemblance of the flow curves in Figure 7 to those in the emulsions showing droplet break up modelled by Jansen et al [35] is striking. …”

Section: Emulsions Inspection Of the T-t G Values Insupporting

confidence: 73%

Low shear rheological behaviour of two-phase mesophase pitch

Ramjee

Rand

Focke

2015

Carbon

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“…A broad set of data for drops deformation and break up, including a large class of two-dimensional (2D)-flows-covering from simple shear up to a purely elongational flow-was provided by Bentley and Leal [28]. More recently, for emulsions subjected to simple shear flows, Jansen [29] has shown that the critical capillary number decreases with increments of the fraction of the disperse phase: Ca rup (p, φ). Droplet-breaking mechanisms and shapes of Newtonian liquid droplets have been extensively studied.…”

Section: Breakup Of Droplets Under a Shearing Flowmentioning

confidence: 99%

Evolution of the Size Distribution of an Emulsion under a Simple Shear Flow

Leiva

Geffroy

2018

Fluids

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Understanding the rheology of immiscible liquids mixtures, as well as the role played by its micro-structures are important criteria for the production of new materials and processes in industry. Here, we study changes over time of the droplet size distributions of emulsions induced by slow shearing flows. We observe that the initial heterogeneous microstructure may evolve toward more complex structures (such as bimodal distribution) as a result of coalescence and rupture of droplets. These dynamic structures were produced using a flow cell made up of two parallel disks, separated by a gap of 100 µm. The steady rotation of the lower disk generates a simple shear flow of 2 of 15 r rates. Despite the possible relevance of the latter, here, we address f the emulsion at low shear rates and in the relevance to the rheology responds to the low, dimensionless time evolutions induced by slow ork.lished on the effects of the history of the shear rate (e.g., on the rop, or coalescence of quasi-equal size drops). The pioneering work t deformation of a single drop establishes experimentally that two etermine the drop deformation under a linear flow: the capillary rger capillary numbers induce larger drop deformations, and viscous r capillary number in order to deform significantly. n by Equation (1)e viscosity of the fluid matrix, the radius of the drop, the applied ion coefficient between phases, respectively. he two phases is given by Equation (2)perse fluid, and η m is the viscosity of the continuum fluid or matrix. nder flow (besides deformation of drops), other phenomena can alescence of drops [4], break up of drops [6], or capture of a rather larger drop [14]. When applying a larger shear rate to the emulsion, ed and are frequently the main source of the observed dynamical drops; although, each phenomenon depends most likely on different flows, coalescence of small, equal-sized drops is observed, and the rates of deformation, especially with low viscosity fluids. Research tions under shearing flows, even beyond a critical drop size (up droplets), are given in [15][16][17]. The growth of drops through the droplets-by a mechanism that appears to resemble an Oswald produced but requires a rather broad size distribution, including ing distributions of particles induced by flow have been observed as phenomena is less well documented. Here, we attempt to describe a low-shear-flow phenomena, which generally modifies the observed r complex and nonlinear manner.nism occurs mainly in the weakest of flows. During this process, end enough time in close proximity. Thus, a dimensionless time, τ, quired for a high probability of coalescence (or its efficiency) can betion of imposed flow of the experiment, while the shear rate,.γ, ions of drops of a given size. Please note that it is customary to ation measure, but here, we prefer to associate the inverse of this cy or efficiency of coalescence. Dimensionless deformation measures = 0.75 s −1 , during ∼ 400 s. After a brief rest time, this procedure was repeated by applying ...

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“…For Ca just above CaC the droplet typically breaks into two fragments, while for Ca >> CaC it stretches into a long fluid thread that breaks into many fragments. For non-Newtonian continuous phases (e.g., non-dilute emulsions or continuous phases with thickeners) the continuous phase viscosity is usually replaced by the apparent emulsion viscosity at the prevailing shear rates (e.g., [9,12,17]). …”

Section: Droplet Break-up In 2d Linear Flowsmentioning

confidence: 99%

Computational Fluid Dynamics (CFD)-Based Droplet Size Estimates in Emulsification Equipment

Janssen

Mayer²

2016

Processes

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While academic literature shows steady progress in combining multi-phase computational fluid dynamics (CFD) and population balance modelling (PBM) of emulsification processes, the computational burden of this approach is still too large for routine use in industry. The challenge, thus, is to link a sufficiently detailed flow analysis to the droplet behavior in a way that is both physically relevant and computationally manageable. In this research article we propose the use of single-phase CFD to map out the local maximum stable droplet diameter within a given device, based on well-known academic droplet break-up studies in quasi-steady 2D linear flows. The results of the latter are represented by analytical correlations for the critical capillary number, which are valid across a wide viscosity ratio range. Additionally, we suggest a parameter to assess how good the assumption of quasi-steady 2D flow is locally. The approach is demonstrated for a common lab-scale rotor-stator device (Ultra-Turrax, IKA-Werke GmbH, Staufen, Germany). It is found to provide useful insights with minimal additional user coding and little increase in computational effort compared to the single-phase CFD simulations of the flow field, as such. Some suggestions for further development are briefly discussed.

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Droplet breakup in concentrated emulsions

Cited by 115 publications

References 9 publications

Low shear rheological behaviour of two-phase mesophase pitch

Low shear rheological behaviour of two-phase mesophase pitch

Evolution of the Size Distribution of an Emulsion under a Simple Shear Flow

Computational Fluid Dynamics (CFD)-Based Droplet Size Estimates in Emulsification Equipment

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