Simultaneous visualization of the flow inside and around droplets generated in microchannels

Duxenneuner, Manuela R.; Fischer, Peter; Windhab, Erich J.; Cooper-White, Justin J.

doi:10.1007/s10404-013-1259-9

Cited by 8 publications

(5 citation statements)

References 61 publications

(67 reference statements)

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“…In recent years, advancements in imaging techniques have improved the understanding of capillary-dominated flow substantially (Pak et al 2015;Blois et al 2015;Duxenneuner et al 2014). However, numerical simulation tools are still indispensable for progress in theoretical understanding of the dynamic processes as well as for parameter optimisation (Zhou et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Spontaneous imbibition in a microchannel: analytical solution and assessment of volume of fluid formulations

Pavuluri

Maes

Doster

2018

Microfluid Nanofluid

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The simulation of multi-phase flow at low capillary numbers (Ca) remains a challenge. Approximate computations of the capillary forces tend to induce parasitic currents (PC) around the interface. These PC induce additional viscous dissipation and shear forces that potentially lead to wrong calculations of the general flow dynamics. Here, we focus on the case of spontaneous imbibition in a microchannel of Hele-Shaw cell symmetry with capillarity being the only driving force. We extend the Lucas-Washburn equation to account for arbitrary viscosity ratios and assess four volume-of-fluid (VOF) formulations against the analytical solution. More specifically, we evaluate the continuum surface force (CSF) formulation, the sharp surface force (SSF) formulation, the filtered surface force (FSF) formulation and the piecewise linear interface calculation (PLIC) formulation extended by a higher order discretisation of the interface curvature through a height function with respect to accuracy, performance and heuristic parameters. We quantify PC for each formulation and investigate their impact on flow with Ca < 10 −2. The magnitude of PC are largest for CSF and are reduced two fold by SSF. FSF reduces PC considerably more but shows periodic short bursts in the velocity field. PLIC shows no PC for the studied Ca and viscosity ratios. However, it fails when a denser fluid displaces a lighter fluid. Despite PC, all formulations are accurate within 10%. PLIC is suited to serve as a reference but relies on a structured mesh and is computationally expensive. FSF requires more heuristic parameters. Together with periodic bursts, this prevents a conclusive statement on the best choice between SSF and FSF.

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Section: Introductionmentioning

confidence: 99%

Spontaneous imbibition in a microchannel: analytical solution and assessment of volume of fluid formulations

Pavuluri

Maes

Doster

2018

Microfluid Nanofluid

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“…Also important to microfluidic applications is the formation processes used to generate droplets or bubbles. Recently, Duxenneuner et al 22 investigated the formation of droplets via liquid-liquid dispersion (injection) with both Newtonian and non-Newtonian fluids as the immersed phase. Using micro digital particle image velocimetry (µ-DPIV) they measured the flow both inside the forming droplets as well as outside in the continuous phase.…”

Section: Introductionmentioning

confidence: 99%

Droplets in an axisymmetric microtube: Effects of aspect ratio and fluid interfaces

DeVoria

Mohseni

2015

Physics of Fluids

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The flow within a liquid droplet steadily translating along an axisymmetric microtube is investigated experimentally and compared with a model to predict the invariants of the flow, that is circulation, hydrodynamic impulse, and kinetic energy. The model is based on pipe Poiseuille flow and allows for variable aspect ratio, AR. The invariants are computed from the velocity fields, which are measured with micro digital particle image velocimetry. The non-dimensionalized experimental invariants show negligible dependence on the Reynolds number, within the small range investigated (∼1.5-13), which also agrees with the model. The effect of introducing a fluid interface is found to increase the observed magnitude of invariants in low-AR droplets above those in continuous flow. Also increased are the average rates at which invariants are advected across a hypothetical flux plane within the tube. The increase in these rates above continuous flow goes as AR−1. The momentum flux is similarly increased for low-AR and is mainly attributed to the converging/diverging radial velocities near the trailing/leading interfaces. The momentum flux is also compared with available synthetic jet data.

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“…Based on microfluidic technology, extensive investigations, both experimental and numerical, have been conducted on the internal flow of a droplet during its formation and the subsequent moving stages in microchannels [5][6][7][8]. Micro-PIV (Particle Image Velocimetry) technology is the main experimental method used to explore the droplet's internal flow field [6][7][8][9][10][11][12][13]; and numerical methods include the CFD method [14][15][16][17][18][19], Lattice Boltzmann method [20,21], immersed-boundary [22], etc. ; and the research systems include absorption [23], extraction [24][25][26], mixing [27,28], reaction [29,30], condensation [31], evaporation [32,33], functional materials [34,35] and double emulsion droplet [36], etc.…”

Section: Introductionmentioning

confidence: 99%

Substance transfer behavior controlled by droplet internal circulation

Wang

et al. 2020

Chemical Engineering Journal

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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Simultaneous visualization of the flow inside and around droplets generated in microchannels

Cited by 8 publications

References 61 publications

Spontaneous imbibition in a microchannel: analytical solution and assessment of volume of fluid formulations

Spontaneous imbibition in a microchannel: analytical solution and assessment of volume of fluid formulations

Droplets in an axisymmetric microtube: Effects of aspect ratio and fluid interfaces

Substance transfer behavior controlled by droplet internal circulation

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