Relevant bibliographies by topics / Mixing at Microscale

Academic literature on the topic 'Mixing at Microscale'

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Published: 6 September 2023

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Journal articles on the topic "Mixing at Microscale"

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Ober, Thomas J., Daniele Foresti, and Jennifer A. Lewis. "Active mixing of complex fluids at the microscale." Proceedings of the National Academy of Sciences 112, no. 40 (September 22, 2015): 12293–98. http://dx.doi.org/10.1073/pnas.1509224112.

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Mixing of complex fluids at low Reynolds number is fundamental for a broad range of applications, including materials assembly, microfluidics, and biomedical devices. Of these materials, yield stress fluids (and gels) pose the most significant challenges, especially when they must be mixed in low volumes over short timescales. New scaling relationships between mixer dimensions and operating conditions are derived and experimentally verified to create a framework for designing active microfluidic mixers that can efficiently homogenize a wide range of complex fluids. Active mixing printheads are then designed and implemented for multimaterial 3D printing of viscoelastic inks with programmable control of local composition.
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Heyman, Joris, Daniel R. Lester, Régis Turuban, Yves Méheust, and Tanguy Le Borgne. "Stretching and folding sustain microscale chemical gradients in porous media." Proceedings of the National Academy of Sciences 117, no. 24 (May 28, 2020): 13359–65. http://dx.doi.org/10.1073/pnas.2002858117.

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Fluid flow in porous media drives the transport, mixing, and reaction of molecules, particles, and microorganisms across a wide spectrum of natural and industrial processes. Current macroscopic models that average pore-scale fluctuations into an effective dispersion coefficient have shown significant limitations in the prediction of many important chemical and biological processes. Yet, it is unclear how three-dimensional flow in porous structures govern the microscale chemical gradients controlling these processes. Here, we obtain high-resolution experimental images of microscale mixing patterns in three-dimensional porous media and uncover an unexpected and general mixing mechanism that strongly enhances concentration gradients at pore-scale. Our experiments reveal that systematic stretching and folding of fluid elements are produced in the pore space by grain contacts, through a mechanism that leads to efficient microscale chaotic mixing. These insights form the basis for a general kinematic model linking chaotic-mixing rates in the fluid phase to the generic structural properties of granular matter. The model successfully predicts the resulting enhancement of pore-scale chemical gradients, which appear to be orders of magnitude larger than predicted by dispersive approaches. These findings offer perspectives for predicting and controlling the vast diversity of reactive transport processes in natural and synthetic porous materials, beyond the current dispersion paradigm.
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Enfield, Kent, Jeremy Siekas, and Deborah Pence. "LAMINATE MIXING IN MICROSCALE FRACTAL-LIKE MERGING CHANNEL NETWORKS." Microscale Thermophysical Engineering 8, no. 3 (January 2004): 207–24. http://dx.doi.org/10.1080/10893950490477383.

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Sun, Chen-li, and Tzu-hsun Hsiao. "Quantitative analysis of microfluidic mixing using microscale schlieren technique." Microfluidics and Nanofluidics 15, no. 2 (February 15, 2013): 253–65. http://dx.doi.org/10.1007/s10404-013-1148-2.

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VERGUET, STÉPHANE, CHUANHUA DUAN, ALBERT LIAU, VEYSEL BERK, JAMIE H. D. CATE, ARUN MAJUMDAR, and ANDREW J. SZERI. "Mechanics of liquid–liquid interfaces and mixing enhancement in microscale flows." Journal of Fluid Mechanics 652 (May 19, 2010): 207–40. http://dx.doi.org/10.1017/s0022112009994113.

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Experimental work on mixing in microfluidic devices has been of growing importance in recent years. Interest in probing reaction kinetics faster than the minute or hour time scale has intensified research in designing microchannel devices that would allow the reactants to be mixed on a time scale faster than that of the reaction. Particular attention has been paid to the design of microchannels in order to enhance the advection phenomena in these devices. Ultimately, in vitro studies of biological reactions can now be performed in conditions that reflect their native intracellular environments. Liau et al. (Anal. Chem., vol. 77, 2005, p. 7618) have demonstrated a droplet-based microfluidic mixer that induces improved chaotic mixing of crowded solutions in milliseconds due to protrusions (‘bumps’) on the microchannel walls. Liau et al. (2005) have shown it to be possible to mix rapidly plugs of highly concentrated protein solutions such as bovine hemoglobin and bovine serum albumin. The present work concerns an analysis of the underlying mechanisms of shear stress transfer at liquid–liquid interfaces and associated enhanced mixing arising from the protrusions along the channel walls. The role of non-Newtonian rheology and surfactants is also considered within the mixing framework developed by Aref, Ottino and Wiggins in several publications. Specifically, we show that proportional thinning of the carrier fluid lubrication layer at the bumps leads to greater advection velocities within the plugs, which enhances mixing. When the fluid within the plugs is Newtonian, mixing will be enhanced by the bumps if they are sufficiently close to one another. Changing either the rheology of the fluid within the plugs (from Newtonian to non-Newtonian) or modifying the mechanics of the carrier fluid-plug interface (by populating it with insoluble surfactants) alters the mixing enhancement.
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Zhou, Ran, Athira N. Surendran, Marcel Mejulu, and Yang Lin. "Rapid Microfluidic Mixer Based on Ferrofluid and Integrated Microscale NdFeB-PDMS Magnet." Micromachines 11, no. 1 (December 25, 2019): 29. http://dx.doi.org/10.3390/mi11010029.

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Ferrofluid-based micromixers have been widely used for a myriad of microfluidic industrial applications in biochemical engineering, food processing, and detection/analytical processes. However, complete mixing in micromixers is extremely time-consuming and requires very long microchannels due to laminar flow. In this paper, we developed an effective and low-cost microfluidic device integrated with microscale magnets manufactured with neodymium (NdFeB) powders and polydimethylsiloxane (PDMS) to achieve rapid micromixing between ferrofluid and buffer flow. Experiments were conducted systematically to investigate the effect of flow rate, concentration of the ferrofluid, and micromagnet NdFeB:PDMS mass ratio on the mixing performance. It was found that mixing is more efficient with lower total flow rates and higher ferrofluid concentration, which generate greater magnetic forces acting on both streamwise and lateral directions to increase the intermixing of the fluids within a longer residence time. Numerical models were also developed to simulate the mixing process in the microchannel under the same conditions and the simulation results indicated excellent agreements with the experimental data on mixing performance. Combining experimental measurements and numerical simulations, this study demonstrates a simple yet effective method to realize rapid mixing for lab-on-chip systems.
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Folkard, Andrew. "The Multi-Scale Layering-Structure of Thermal Microscale Profiles." Water 13, no. 21 (November 1, 2021): 3042. http://dx.doi.org/10.3390/w13213042.

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Thermal microstructure profiling is an established technique for investigating turbulent mixing and stratification in lakes and oceans. However, it provides only quasi-instantaneous, 1-D snapshots. Other approaches to measuring these phenomena exist, but each has logistic and/or quality weaknesses. Hence, turbulent mixing and stratification processes remain greatly under-sampled. This paper contributes to addressing this problem by presenting a novel analysis of thermal microstructure profiles, focusing on their multi-scale stratification structure. Profiles taken in two small lakes using a Self-Contained Automated Micro-Profiler (SCAMP) were analysed. For each profile, buoyancy frequency (N), Thorpe scales (LT), and the coefficient of vertical turbulent diffusivity (KZ) were determined. To characterize the multi-scale stratification, profiles of d2T/dz2 at a spectrum of scales were calculated and the number of turning points in them counted. Plotting these counts against the scale gave pseudo-spectra, which were characterized by the index D of their power law regression lines. Scale-dependent correlations of D with N, LT and KZ were found, and suggest that this approach may be useful for providing alternative estimates of the efficiency of turbulent mixing and measures of longer-term averages of KZ than current methods provide. Testing these potential uses will require comparison of field measurements of D with time-integrated KZ values and numerical simulations.
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Davidson, Max, Paul Dommersnes, Martin Markström, Jean-Francois Joanny, Mattias Karlsson, and Owe Orwar. "Fluid Mixing in Growing Microscale Vesicles Conjugated by Surfactant Nanotubes." Journal of the American Chemical Society 127, no. 4 (February 2005): 1251–57. http://dx.doi.org/10.1021/ja0451113.

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Dzwinel, W., W. Alda, M. Pogoda, and D. A. Yuen. "Turbulent mixing in the microscale: a 2D molecular dynamics simulation." Physica D: Nonlinear Phenomena 137, no. 1-2 (March 2000): 157–71. http://dx.doi.org/10.1016/s0167-2789(99)00177-3.

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Dürauer, Astrid, Stefanie Hobiger, Cornelia Walther, and Alois Jungbauer. "Mixing at the microscale: Power input in shaken microtiter plates." Biotechnology Journal 11, no. 12 (July 14, 2016): 1539–49. http://dx.doi.org/10.1002/biot.201600027.

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Dissertations / Theses on the topic "Mixing at Microscale"

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De, Anindya Kanti. "Numerical Modeling of Microscale Mixing Using Lattice Boltzmann Method." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/27425.

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Recent advancements in microfabrication technology have led to the development of micro-total analytical systems (μ-TAS), more popularly known as lab-on-a-chip (LOC) devices. These devices have a relatively small size and are capable of performing sample and reagent handling steps together with analytical measurements. Rapid mixing is essential in such microfluidic systems for various applications e.g., biochemical analysis, sequencing or synthesis of nucleic acids, and for reproducible biological processes that involve cell activation, enzyme reactions, and protein folding. In this work a numerical model is developed using a lattice Boltzmann method (LBM) to study microscale mixing. The study involves two mixing methods, namely, electroosmotic mixing and magnetic assisted mixing. A single component LBM model is developed to study electroosmotic flow in a square cavity. Mixing is studied by introducing two types of tracer particles in the steady electroosmotic flow and characterized by various mixing parameters. The results show that rapid mixing can be achieved by using a steady electric field and a homogeneous zeta potential. A multicomponent LBM method is also developed to study magnetic assisted mixing in a channel configuration. The ferrofluid flow is influenced by two magnets placed across a microchannel. The interacting field induced by these magnets promotes cross-stream motion of the ferrofluid, which induces its mixing with the other nonmagnetic fluid. Two fluids, one magnetic and another non-magnetic fluid, are introduced in a channel, when two magnets are placed across it at a distance apart. In the presence of the magnetic field, the magnetic fluid tries to follow a zig-zag motion generating two rolls of vortices thereby enhancing mixing. A parametric study characterizes the effects of diffusivity, magnetic field strength, and relative magnet positions on a mixing parameter. Mixing is enhanced when the magnetic field strength and diffusivity are increased. However, contrary to the observed trend, placing the magnets very close to each other axially results in local ferrofluid agglomeration rather than promoting mixing.
Ph. D.
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Enfield, Kent E. "Laminate mixing in microscale fractal-like merging channel networks." Thesis, 2003. http://hdl.handle.net/1957/32377.

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A two-dimensional model was developed to predict concentration profiles from passive, laminar mixing of concentration layers formed in a fractal-like merging channel network. Both flat and parabolic velocity profiles were used in the model. A physical experiment was used to confirm the results of the model. Concentration profiles were acquired in the channels using laser induced fluorescence. The degree of mixing was defined and used to quantify the mixing in the test section. Although the results of the experiment follow the trend predicted by the two-dimensional model, the model under predicts the results of the experiment. A three-dimensional CFD model of the flow field in the channel network was used to explain the discrepancies between the two-dimensional model and the experiment. For the channel network considered, the degree of mixing is a function of Peclet number. The effect of geometry on the degree of mixing is investigated using the two-dimensional model by varying the flow length, the width of the inlet channels, and the number of branching levels. A non-dimensional parameter is defined and used to predict an optimum number of branching levels to maximize mixing for a fixed inlet channel width, total length, and channel depth.
Graduation date: 2003
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Cola, Baratunde Aole. "Optimization of a pulsed source-sink microscale mixing device." Diss., 2004. http://etd.library.vanderbilt.edu/ETD-db/available/etd-12052004-230748/.

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Books on the topic "Mixing at Microscale"

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M, Ottino J., Wiggins Stephen, and Royal Society (Great Britain), eds. Transport and mixing at the microscale: Papers of a theme issue. London: Royal Society, 2004.

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Book chapters on the topic "Mixing at Microscale"

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Afzal, Arshad, and Kwang-Yong Kim. "Mixing at Microscale." In SpringerBriefs in Applied Sciences and Technology, 1–10. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-33-4291-0_1.

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Sammet, C., W. Krieger, M. Völcker, and H. Walther. "A New Mechanism for Laser-Frequency Mixing in a Scanning Tunneling Microscope." In Photons and Local Probes, 257–68. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0423-4_22.

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"Mixing." In Microfluidics and Lab-on-a-Chip, 113–27. The Royal Society of Chemistry, 2020. http://dx.doi.org/10.1039/9781782628330-00113.

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The aim of microfluidic mixing is to achieve thorough and rapid mixing of multiple samples in microscale devices. Microfluidic mixing is achieved by enhancing the diffusion effect between the flows of different species. Induction of chaotic advection effects has proven time and time again to increase the contact surface and contact time between the species flows. Two types of micromixers, passive and active, are explored, with a focus on passive mixers.
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Conference papers on the topic "Mixing at Microscale"

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Hohreiter, V., Jacob N. Chung, E. Cummings, and T. Postlethwaite. "EFFECTS OF SYSTEM DIMENSION ON TURBULENCE AND MICROFLUIDIC MIXING." In Heat Transfer and Transport Phenomena in Microscale. Connecticut: Begellhouse, 2023. http://dx.doi.org/10.1615/1-56700-150-5.360.

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Ergin, F. Go¨khan, Bo Beltoft Watz, Kaspars Erglis, and Andrejs Cebers. "Poor-Contrast Particle Image Processing in Microscale Mixing." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24900.

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Particle image velocimetry (PIV) often employs the cross-correlation function to identify average particle displacement in an interrogation window. The quality of correlation peak has a strong dependence on the signal-to-noise ratio (SNR), or contrast of the particle images. In fact, variable-contrast particle images are not uncommon in the PIV community: Strong light sheet intensity variations, wall reflections, multiple scattering in densely-seeded regions and two-phase flow applications are likely sources of local contrast variations. In this paper, we choose an image pair obtained in a micro-scale mixing experiment with severe local contrast gradients. In regions where image contrast is sufficiently poor, the noise peaks cast a shadow on the true correlation peak, producing erroneous velocity vectors. This work aims to demonstrate that two image pre-processing techniques — local contrast normalization and Difference of Gaussian (DoG) filter — improve the correlation results significantly in poor-contrast regions.
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Balasubramaniam, Lakshmi, Rerngchai Arayanarakool, Samuel D. Marshall, Bing Li, Poh Seng Lee, and Peter C. Y. Chen. "Mixing Enhancement in Spiral Microchannels." In ASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/mnhmt2016-6422.

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Advancements in the field of microfluidics has led to an increasing interest to study laminar flow in microchannel and its potential applications. Understanding mixing at a microscale can be useful in various biological, heating and industrial applications due to the space and time reduction that micro mixing permits. This work aims to study mixing enhancement due to curved microchannel and the influence of varying microchannel cross sectional shape through numerical and experimental investigations. Unlike prior studies which use channel dimensions in the lower microscale range, this work has been conducted on channels with dimensions in the higher end of micrometer range. Using a cross sectional hydraulic diameter of 600 μm enables introduction of flow into the curved channel at a Reynolds Number ranging from 0.15 to 75, the findings of which show considerable improvement in the mixing performance as compared to that of equivalent straight channels, due to the development of secondary flows known as Dean Vortices.
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Walsh, E. J., and R. Grimes. "A Micromixer Based Upon Buoyancy." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79942.

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A novel micromixer is presented which may be thermally controlled to allow for the enhanced mixing of different species at the microscale. Numerical simulations are presented which demonstrate the operation of the design and methodologies for the generation of different microfluidic structures to enhance mixing at the microscale. It is found that buoyancy may be implemented to create a range of mixing regimes at the microscale. The generation of such fluidic structures allows the controlled mixing of different species
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Fazeli, Abdy, and Saeed Moghaddam. "Microscale Phase Separation Through Nanoporous Membranes." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17633.

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This paper presents an experimental study on bubbles extraction from a two-phase flow in microchannels. The bubbles were extracted through a hydrophobic porous membrane covering the microchannels. The two-phase flow was generated through mixing water and air at a T-junction positioned before a microchannel on a microfabricated device. To study the effect of different parameters on the extraction rate, an extensive parametric study was conducted. The parametric space included variations of the channel depth, pressure difference across the membrane, and water and air flow rates. Differential pressure across the membrane was found to be the most critical factor impacting the bubbles extraction rate. Also, the effect of flow quality on the extraction rate was determined to be insignificant. Furthermore, it was found that at a critical velocity a liquid layer forms between the bubbles and the membrane and consequently the bubbles cease to extract.
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Yu, Tak For, Sylvanus Yuk Kwan Lee, Yitshak Zohar, and Man Wong. "Instability Modes of Two-Phase Flows in a Mixing-Layer Microdevice." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/mems-23883.

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Abstract Extensive development of biomedical and chemical analytic microdevices involves microscale fluid flows. Merging of fluid streams is expected to be a key feature in such devices. An integrated microsystem consisting of merging microchannels and distributed pressure microsensors has been designed and characterized to study this phenomenon on a microscale. The two narrow, uniform and identical channels merged smoothly into a wide, straight and uniform channel downstream of a splitter plate. All of the devices were fabricated using standard micromachining techniques. Mass flow rates and pressure distributions were measured for single-phase gas flow in order to characterize the device. The experimental results indicated that the flow developed when both inlets were connected together to the gas source could be modeled as gas flow through a straight and uniform microchannel. The flow through a single branch while the other was blocked, however, could be modeled as gas flow through a pair of microchannels in series. Flow visualizations of two-phase flows have been conducted when driving liquid and gas through the inlet channels. Several instability modes of the gas/liquid interface have been observed as a function of the pressure difference between the two streams at the merging location.
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Chamarthy, Pramod, Steven T. Wereley, and Suresh V. Garimella. "Microscale Laser-Induced Fluorescence Method for Non-Intrusive Temperature Measurement." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41935.

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Ratiometric Laser Induced Fluorescence (LIF) Thermometry is applied for temperature measurements in a ‘T’ junction, using microscale visualization methods. Rhodamine B (RhB) and Rhodamine 110 (Rh110) are used as the temperature-dependent and temperature-independent dye, respectively. The temperature responses of the two dyes were carefully measured for different concentrations. A novel normalization procedure for the calibration curve is proposed to render the technique system-independent. The mixing plane between a hot and a cold fluid stream for three different temperatures and three different flow rate ratios is visualized using 4X and 10X magnifications.
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Hoffmann, Marko, Michael Schlu¨ter, and Norbert Ra¨biger. "Experimental Characterization of Micro Mixers Using Microscale-Laser Induced Fluorescence and Particle Image Velocimetry." In ASME 4th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2006. http://dx.doi.org/10.1115/icnmm2006-96132.

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Microreactors are basic components of microfluidic systems for chemical and biochemical applications and the large area-to-volume ratio of micro-reactors enables a higher yield and selectivity than conventionally designed processes. To take advantage of the full potential of this ambitious technology, a fundamental understanding of the transport processes on the relevant time and length scales is necessary. Besides the approach of using commercial CFD programs for numerical flow visualization, the microscale fluid flow visualization is an important tool for acquiring localized flow information within these microreactors. To get a deeper insight the mixing characteristic of different T-shaped micro mixers with rectangular cross sections (dimensions: 100–400 micron) has been investigated by means of the non-invasive measurement techniques micro-Laser induced fluorescence (micro-LIF) and micro-Particle Image Velocimetry (micro-PIV). The analysis of the concentration fields proves that with a higher Re a stretching and thinning of liquid lamellae (vortex generation) occurs, causing an enlarged interfacial surface area and consequently leading to a better mixing performance by diffusion. The analysis of the velocity fields shows further the existence of a three dimensional flow in the entrance region of the mixing channel of a T-shaped micro mixer.
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Thomas, Susan, and Tim Ameel. "Moderate Reynolds Number Mixing in a T-Channel." In ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels collocated with 3rd Joint US-European Fluids Engineering Summer Meeting. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30159.

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An experimental investigation of water flow in a T-shaped channel with rectangular cross section (20 × 20 mm inlet ID and 20 × 40 mm outlet ID) has been conducted for a Reynolds number Re range of 56 to 422, based on inlet diameter. Dynamical conditions and the T-channel geometry of the current study are applicable to the microscale. This study supports a large body of numerical work, and resolution and the interrogation region are extended beyond previous experimental studies. Laser induced fluorescence (LIF) and particle imaging velocimetry (PIV) are used to characterize flow behaviors over the broad range of Re where realistic T-channels operate. Scalar structures previously unresolved in the literature are presented. Special attention is paid to the unsteady flow regimes that develop at moderate Re, which significantly impact mixing but are not yet well characterized or understood. An unsteady symmetric topology, which develops at higher Re and negatively impacts mixing, is presented, and mechanisms behind the wide range of mixing qualities predicted for this regime are explained. An optimal Re operating range is identified based on multiple experimental trials.
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Loire, Sophie, Paul Kauffmann, Paul Gimenez, Igor Mezić, and Carl Meinhart. "Electrothermal Blinking Vortices for Chaotic Mixing." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-88269.

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Thanks to its favorable reduction scale law, and its easy integration, electrokinetics has emerged over the last fifteen years as one of the major solution to drive flows in fully integrated lab-on-chip. At microscale, an efficient mixing is a keystep which can dramatically accelerate bio-reactions. For thirty years, Dynamical System theory has predicted that chaotic mixing must involve at least 3 dimensions (either time dependent 2D flows or 3D flows). However, in microfluidics, few works have yet presented efficient embedded micromixers. This paper presents experimental and theoretical study of 2D time dependent chaotic mixing using AC electrothermal fluid flows. Experiments and numerical simulations are performed on a top view device and a sideview device. In both devices, a sinusoidal electric signal is applied between 3 interdigitated gold electrodes. A phase signal Vpp = 11V and a ground are switched between the two side electrodes using a step function, whereas the opposite phase signal –Vpp is steadily applied to the center electrode (Figure 1). Flow velocity is measured by micro particle image velocimetry μ PIV. The velocity profile shows a dramatic asymmetry between the two vortices. Therefore, during the switch, vortices overlap, leading to stretching and folding flows required to obtain chaotic mixing (Figure 3 and 4). The experimental measurements validate our electrothermal models based on our previous work [1]. The mixing efficiency of low diffusive particles is studied at multiscale using the mix-variance coefficient (MVC) [2] to evaluate mixing at different scales (Figure 4). To do so, the domain is successively divided in boxes along the x and y direction up to nx and ny boxes, respectively. For each box configuration, average bead concentration is computed. The variance of these concentrations is then evaluated: MVCs=1nxny∑i=1ny∑j=1nxρij-0.52. The result of numerically evaluated MVC in Figure 2 show a dramatic increase of mixing efficiency with blinking vortices compared to steady flow. Theoretical, experimental and simulation results of the mixing process will be presented.
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