Simulation of the double emulsion formation through a hierarchical T-junction microchannel

Abstract

Purpose – The purpose of this paper is to present a practical way to create three kinds of double emulsions such as double emulsion, double-component double emulsion and viscoelastic double emulsion. Design/methodology/approach – A hierarchical T-junction microfluidic device is selected to simulate this phenomenon. A system of the three-phase flows consists of the inner, middle and outer phases were simulated by the direct numerical simulation (DNS) method. The dripping regime is considered for the droplet formation in both T-junctions. The adaptive mesh refinement technique is used to simulate the droplet formation and determine the interface rupture. Findings – The one-step and two-step encapsulation are used to create the double emulsion and the viscoelastic double emulsion, respectively. In both T-junctions, droplets are created by the balance of three parameters which are instability, viscous drag and pressure buildup. The one-step formation of double emulsion is presented for encapsulates the viscoelastic fluid. Originality/value – The simulated hierarchical microchannel shows some desirable features for creating the complex compounds. The encapsulation process is simulated in micro-scale that is useful for drug delivery applications.

Passive microinjection within high-throughput microfluidics for controlled actuation of droplets and cells

“…The double emulsion is then gently marched to the downstream microchannel (Supplementary Video SV1). The passive scenario of microinjection begins with the interaction of the Current and Droplet phases at the T-junction, where the dripping instability separates the Droplet phase to droplets marching them downstream with a defined size and immutable distance from each other 10 . There are five possible droplet formation regimes of Squeezing, Transition, Dripping, Jetting and parallel due to the instability at the T-junction, which manages the duration of each injection cycle and period of droplet formation.…”

“…where subscripts Cu, D and I are the Current, Droplet and Injected phases, respectively 2 . The cells containing multiphase interfaces are not considered as a homogenous mixture, while the phases are separated from each other with a piecewise-linear VOF scheme 10,45,47,48 . For each cell of the mesh, the surface tension force imposed on the interface represents the interaction of different phases (eq.…”

“…AMR technique focuses on the regions of importance, for example where singularities may affect the accuracy of numerical simulation (e.g., sharp corners of the microchannel); where the gradient of physical parameters is high at the site of detachment and interface rupture; and at the gap between the droplet and microchannel walls 49 . The curvature, topology and value-based refinement are exploited concurrently to preserve numerical accuracy and robustness 2,10,47,48 (Fig. S4).…”

“…The success of passive microinjection within microfluidics is heavily dependent on parameters adjustment which necessitates the development of a 3D numerical model for the accurate control of flow and injection parameters. Analytical and numerical methods have been developed to model the physics of double emulsion formation 2,10,14,40 . We previously developed a three-dimensional (3D) model to simulate a hierarchical T-junction microchannel for creating the structure of double emulsion 2,41 , double-component double emulsion, and viscoelastic double emulsion 10 .…”

“…Analytical and numerical methods have been developed to model the physics of double emulsion formation 2,10,14,40 . We previously developed a three-dimensional (3D) model to simulate a hierarchical T-junction microchannel for creating the structure of double emulsion 2,41 , double-component double emulsion, and viscoelastic double emulsion 10 . However, due to the complexity of the 3D numerical model and the needs to adjust a large number of parameters, there is no report on modeling the passive microinjection of an immiscible fluid into droplets formed within microfluidics.…”