Effective mixing in a short serpentine split-and-recombination micromixer

Raza, Wasim; Hossain, Shakhawat; Kim, Kwang‐Yong

doi:10.1016/j.snb.2017.11.135

Cited by 82 publications

(55 citation statements)

References 31 publications

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“…The serpentine micromixers have lower mixing costs than the chicanes micromixer, because of higher pressure losses due to right-angle geometry, which leads to a moderate intensification of the mixing. The further increasing of the channel complexity, as shown for serpentine 3D splitting and recombination-type (SAR) micromixers [42,43], causes higher energy dissipation and pressure drops up to 40 kPa at Reynolds number of 50. The generated saddle-shaped flow structure promotes chaotic advection and complete mixing at the micromixer outlet.…”

Section: Pressure Dropmentioning

confidence: 99%

Numerical and Experimental Investigations of a Micromixer with Chicane Mixing Geometry

2018

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A micromixer is a new type of chemical engineering equipment used to intensify the mixing process. This article provides details on flow regimes in microchannels with a complex geometry, such as with chicane mixing geometry. Experiments involving water, ink, and a micro digital camera have determined both the micromixer’s initial mixing zone, and also the streamlines. Computational fluid dynamics (CFD) modelling helped identify the mechanism of stimulating effect; swirling and recirculation were identified as two special cases of the convective mixing process. To characterize the degree of mixing, a function of volume flow rate was proposed. A much higher degree of mixing in vortex flow compared to stratified flow was observed. The relationship between laminar flow and vortices shows a square-law dependence of pressure drop against the volume flow rate. The mixing cost and the mixing energy cost at Reynolds number of 50 are higher for the chicane micromixer than for micromixers without chicanes geometry.

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Section: Pressure Dropmentioning

confidence: 99%

Numerical and Experimental Investigations of a Micromixer with Chicane Mixing Geometry

2018

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“…For instance, the selected mesh level in References [19,25] was primarily considered to resolve the flow field instead of solute transport although quite high Peclet numbers (e.g., on the order 10 4 -10 6 ) were examined. In several papers [14,17,27,28], very close mesh densities were employed for grid studies which implies that the effects of numerical diffusion cannot be revealed clearly. In these applications, numerical simulations may be considered as grid-independent with a minimal error percentage even though a serious amount of error remains in the reported results.…”

Section: Numerical Diffusion In Fluid Flow and Scalar Transport (Dmentioning

confidence: 99%

Computational Evaluation of Mixing Performance in 3-D Swirl-Generating Passive Micromixers

Okuducu

Aral

2019

Processes

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Computational Fluid Dynamics (CFD) tools are used to investigate fluid flow and scalar mixing in micromixers where low molecular diffusivities yield advection dominant transport. In these applications, achieving a numerical solution is challenging. Numerical procedures used to overcome these difficulties may cause misevaluation of the mixing process. Evaluation of the mixing performance of these devices without appropriate analysis of the contribution of numerical diffusion yields over estimation of mixing performance. In this study, two- and four-inlet swirl-generating micromixers are examined for different mesh density, flow and molecular diffusivity scenarios. It is shown that mesh densities need to be high enough to reveal numerical diffusion errors in scalar transport simulations. Two-inlet micromixer design was found to produce higher numerical diffusion. In both micromixer configurations, when cell Peclet numbers were around 50 and 100 for Reynolds numbers 240 and 120, the numerical diffusion effects were tolerable. However, when large cell Peclet number scenarios were tested, it was found that the molecular diffusivity of the fluid is completely masked by false diffusion errors.

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“…The mixing performance of other typical micromixers contains shear-thinning fluids involving T-shaped and serpentine microchannels (Afzal A et al [12]), micromixer with Cshaped units (Tsai RT et al [13]), micromixer with curved units (Islami SB et al [15]), micromixer with Curved and Grooved units (Islami SB et al [16]), E-shape split-andrecombine micomixer (He M et al [30]), and the micromixers contains Newtonian fluids, involving two layers with OH-shaped units (Hossain S et al [28]), and recently two layers OX-shaped units (Raza W et al [29]). A quantitative comparison has been carried out to compare the mixing index of our micromixer with those of recent studies on various micromixers as shown in Table 2.…”

Section: The Mixing Performances Of the Tlccm Micromixermentioning

confidence: 99%

High mixing performances of shear-thinning fluids in two-layer crossing channels micromixer at very low Reynolds numbers

Amar

Lasbet

Makhlouf

2019

JMES

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In a recent study, the Two-Layer Crossing Channels Micromixer (TLCCM) exhibited good mixing capacities in the case of the Newtonian fluids (close to 100%) for all considered Reynolds number values. However, since the majority of the used fluids in the industrial sectors are non-Newtonians, this work details the mixing evolution of power-law fluids in the considered geometry. In this paper, the power-law index ranges from 0.73 to 1 and the generalized Reynolds number is bounded between 0.1 and 50. The conservation equations of momentum, mass and species transport are numerically solved using a CFD code, considering the species transport model. The flow structure at the cross-sectional planes of our micromixer was studied using the dynamic systems theory. The evolutions of the intensity, also the axial, radial and tangential velocity profiles were examined for different values of the Reynolds number and the power-law index. Besides, the pressure drop of the power-law fluids under different Reynolds number was calculated and represented. Furthermore, the mixing efficiency is evaluated by the computation of the mixing index (MI), based on the standard deviation of the mass fraction in different cross-sections. In such geometry, a perfect mixing is achieved with MI closed to 99.47 %, at very small Reynolds number (from the value 0.1) whatever the power-law index and generalized Reynolds numbers taken in this investigation. Consequently, the targeted channel presents a useful tool for pertinent mass transfer improvements, it is highly recommended to include it in various microfluidic systems. 5939 the case of creeping flows (Re of the order of 0.1). Temporary perturbation concerns twodimensional flows where solid boundaries and/or initial conditions are disturbed over time.Regarding the spatial perturbation, it makes the geometry twisted in the three directions of space. These perturbations break the flow regularity and so the chaotic flow is generated. For this subject, it became necessary to focus the efforts on the development of micromixers used in the different industrial domains such as bioengineering and chemical engineering, chemical synthesis, emulsion processes, polymerization [1], DNA analysis, two-phase flow separation [2], detection and analysis of chemical or biochemical content [3-4-5]. We can distinguish two main types of micromixers: active and passive micro-mixers [6]. Active micromixers use external energy sources to accentuate the flow agitation by, for example, a magnetic field, pressure field, and electrical field, etc. These types of micromixers are very efficient in terms of mixing [7] but they are more complex and expensive than passive micromixers. In addition, they required more detailed in terms of fabrication. Besides, passive micromixers are of great importance due to their simple structures and easy manufacturing [8]. Thus, the secondary flows resulting from the chaotic advection are very intense and many vortices of different sizes are generated. The large vortices improve the macroscopi...

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Effective mixing in a short serpentine split-and-recombination micromixer

Cited by 82 publications

References 31 publications

Numerical and Experimental Investigations of a Micromixer with Chicane Mixing Geometry

Numerical and Experimental Investigations of a Micromixer with Chicane Mixing Geometry

Computational Evaluation of Mixing Performance in 3-D Swirl-Generating Passive Micromixers

High mixing performances of shear-thinning fluids in two-layer crossing channels micromixer at very low Reynolds numbers

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