scholarly journals Novel 3-D T-Shaped Passive Micromixer Design with Helicoidal Flows

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 637 ◽  
Author(s):  
Mahmut Burak Okuducu ◽  
Mustafa M. Aral
Keyword(s):  
Fluid Flow ◽  
Fluid Mixing ◽  
Mixing Efficiency ◽  
Flow Profile ◽  
Complex Flow ◽  
Mixing Index ◽  
Micro Channels ◽  
Mixing Dynamics ◽  
Passive Micromixer ◽  
Novel Design

Laminar fluid flow and advection-dominant transport produce ineffective mixing conditions in micromixers. In these systems, a desirable fluid mixing over a short distance may be achieved using special geometries in which complex flow paths are generated. In this paper, a novel design, utilizing semi-circular ridges, is proposed to improve mixing in micro channels. Fluid flow and scalar transport are investigated employing Computational Fluid Dynamics (CFD) tool. Mixing dynamics are investigated in detail for alternative designs, injection, and diffusivity conditions. Results indicate that the convex alignment of semi-circular elements yields a specific, helicoidal-shaped fluid flow along the mixing channel which in turn enhances fluid mixing. In all cases examined, homogenous concentration distributions with mixing index values over 80% are obtained. When it is compared to the classical T-shaped micromixer, the novel design increases mixing index and mixing performance values by the factors of 8.7 and 3.3, respectively. It is also shown that different orientations of ridges adversely affect the mixing efficiency by disturbing the formation of helicoidal-shaped flow profile.

Numerical analysis of non-aligned inputs M-type micromixers with different shaped obstacles for biomedical applications

2021 ◽  
pp. 095440892110516
Author(s):  
Muhammad Irfan ◽  
Imran Shah ◽  
Usama M Niazi ◽  
Muhsin Ali ◽  
Sadaqat Ali ◽  
...  
Keyword(s):  
Structural Design ◽  
Biomedical Applications ◽  
Structural Changes ◽  
Nanoparticle Synthesis ◽  
Fluid Mixing ◽  
The Novel ◽  
Flow Conditions ◽  
Mixing Index ◽  
Mixing Performance ◽  
Passive Micromixer

Fluid mixing in lab-on-a-chip devices at laminar flow conditions result in a low mixing index. The reason is dominant diffusion over the convection process. The mixing index can be improved by certain changes in the micromixer structural design like introducing obstacles in the path of fluid flow. These obstacles will make dominant the advection process over the diffusion process. The main contribution of this work is based on proposing the novel hybrid type micromixer design for enhancing the mixing quality. Three non-aligned M-type and non-aligned M-type with obstacles passive type micromixers are analyzed by COMSOL5.5. These designs are hybrid types because different structural changes are combined in a single design for mixing improvement. First of all the straight non-aligned inlets, M-type passive micromixer (SMTM) is analyzed. It is observed that mixing performance is improved because of M-shaped mixing units and non-aligned inlets. This improvement is deemed to be not enough so different shaped obstacles are introduced in the micromixer design. These designs based on obstacles are named horizontal rectangular M-type micromixer, square M-type micromixer, and vertical rectangular M-type micromixer. The mixing index for SMTM, square M-type micromixer, horizontal rectangular M-type micromixer, and vertical rectangular M-type micromixer at Reynolds number Re = 60 is respectively given by 71.1%, 83.21%, 84.45%, and 89.99%. The mixing index of vertical rectangular M-type micromixer was 59.34% − 87.65% for Re = 0.5–100. Vertical rectangular M-type micromixer is concluded with the better-mixing capability design among the proposed ones. Based on these simulation results, the vertical rectangular M-type micromixer design can be utilized for mixing purposes in biomedical applications like nanoparticle synthesis and biomedical sample preparation for drug delivery.

Numerical simulation of three-dimensional passive micromixer based on the principle of Koch fractal

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Siyue Xiong ◽  
Xueye Chen
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Cross Section ◽  
Three Dimensional ◽  
Mixing Efficiency ◽  
Mixing Performance ◽  
Chaotic Convection ◽  
Passive Micromixer ◽  
Koch Fractal ◽  
Koch Fractal Principle

Abstract In this paper, We arrange the obstacles based on the Koch fractal principle (OKF) in the micromixer. By changing the fluid flow and folding the fluid, a better mixing performance is achieved. We improve the mixing efficiency by placing OKF and changing the position of OKF, then we studied the influence of the number of OKF and the height of the micromixer on the mixing performance. The results show that when eight OKF are staggered in the microchannel and the height is 0.2 mm, the mixing efficiency of the OKF micromixer can reach 97.1%. Finally, we compared the velocity cross section and velocity streamline of the fluid, and analyzed the influence of OKF on the concentration trend. Through analysis, it is concluded that OKF can generate chaotic convection in the fluid, and enhance the mixing of fluids by generating vortices and folding the fluid. It can effectively improve the mixing efficiency of the micromixer.

scholarly journals Toward the Next Generation of Passive Micromixers: A Novel 3-D Design Approach

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 372
Author(s):  
Mahmut Burak Okuducu ◽  
Mustafa M. Aral
Keyword(s):  
Molecular Diffusion ◽  
Diffusion Constant ◽  
Interfacial Area ◽  
Laminar Flows ◽  
Fluid Mixing ◽  
Mixing Efficiency ◽  
Maximum Pressure ◽  
Small Diffusion ◽  
Passive Micromixer ◽  
Injection Type

Passive micromixers are miniaturized instruments that are used to mix fluids in microfluidic systems. In microchannels, combination of laminar flows and small diffusion constants of mixing liquids produce a difficult mixing environment. In particular, in very low Reynolds number flows, e.g., Re < 10, diffusive mixing cannot be promoted unless a large interfacial area is formed between the fluids to be mixed. Therefore, the mixing distance increases substantially due to a slow diffusion process that governs fluid mixing. In this article, a novel 3-D passive micromixer design is developed to improve fluid mixing over a short distance. Computational Fluid Dynamics (CFD) simulations are used to investigate the performance of the micromixer numerically. The circular-shaped fluid overlapping (CSFO) micromixer design proposed is examined in several fluid flow, diffusivity, and injection conditions. The outcomes show that the CSFO geometry develops a large interfacial area between the fluid bodies. Thus, fluid mixing is accelerated in vertical and/or horizontal directions depending on the injection type applied. For the smallest molecular diffusion constant tested, the CSFO micromixer design provides more than 90% mixing efficiency in a distance between 260 and 470 µm. The maximum pressure drop in the micromixer is found to be less than 1.4 kPa in the highest flow conditioned examined.

scholarly journals Effect of Thermal Energy and Ultrasonication on Mixing Efficiency in Passive Micromixers

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 891
Author(s):  
Fahizan Mahmud ◽  
Khairul Fikri Tamrin ◽  
Shahrol Mohamaddan ◽  
Nobuo Watanabe
Keyword(s):  
Thermal Energy ◽  
Reynolds Numbers ◽  
Fluid Mixing ◽  
Structural Deformation ◽  
Energy Sources ◽  
Mixing Efficiency ◽  
Mixing Index ◽  
Mixing Performance ◽  
Lower Reynolds Number ◽  
Better Than

Micromixing is a key process in microfluidics technology. However, rapid and efficient fluid mixing is difficult to achieve inside the microchannels due to unfavourable laminar flow. Active micromixers employing ultrasound and thermal energy are effective in enhancing the micromixing process; however, integration of these energy sources within the devices is a non-trivial task. In this study, ultrasound and thermal energy have been extraneously applied at the upstream of the micromixer to significantly reduce fabrication complexity. A novel Dean micromixer was laser-fabricated to passively increase mixing performance and compared with T- and Y-micromixers at Reynolds numbers between 5 to 100. The micromixers had a relatively higher mixing index at lower Reynolds number, attributed to higher residence time. Dean micromixer exhibits higher mixing performance (about 27% better) than T- and Y-micromixers for 40 ≤ Re ≤ 100. Influence of ultrasound and heat on mixing is more significant at 5 ≤ Re ≤ 20 due to the prolonged mechanical effects. It can be observed that mixing index increases by about 6% to 10% once the temperature of the sonicated fluids increases from 30 °C to 60 °C. The proposed method is potentially useful as direct contact of the inductive energy sources may cause unwanted substrate damage and structural deformation especially for applications in biological analysis and chemical synthesis.

scholarly journals Rapid Microfluidic Mixing Method Based on Droplet Rotation Due to PDMS Deformation

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 901
Author(s):  
Chunyang Wei ◽  
Chengzhuang Yu ◽  
Shanshan Li ◽  
Feng Pan ◽  
Tiejun Li ◽  
...  
Keyword(s):  
Chemical Synthesis ◽  
Low Cost ◽  
Cross Flow ◽  
Mixing Efficiency ◽  
Mixing Index ◽  
Microfluidic Mixing ◽  
Microfluidic Mixer ◽  
Passive Micromixer ◽  
Droplet Movement ◽  
Mixing Method

Droplet-based micromixers have shown great prospects in chemical synthesis, pharmacology, biologics, and diagnostics. When compared with the active method, passive micromixer is widely used because it relies on the droplet movement in the microchannel without extra energy, which is more concise and easier to operate. Here we present a droplet rotation-based microfluidic mixer that allows rapid mixing within individual droplets efficiently. PDMS deformation is used to construct subsidence on the roof of the microchannel, which can deviate the trajectory of droplets. Thus, the droplet shows a rotation behavior due to the non-uniform distribution of the flow field, which can introduce turbulence and induce cross-flow enhancing 3D mixing inside the droplet, achieving rapid and homogenous fluid mixing. In order to evaluate the performance of the droplet rotation-based microfluidic mixer, droplets with highly viscous fluid (60% w/w PEGDA solution) were generated, half of which was seeded with fluorescent dye for imaging. Mixing efficiency was quantified using the mixing index (MI), which shows as high as 92% mixing index was achieved within 12 mm traveling. Here in this work, it has been demonstrated that the microfluidic mixing method based on the droplet rotation has shown the advantages of low-cost, easy to operate, and high mixing efficiency. It is expected to find wide applications in the field of pharmaceutics, chemical synthesis, and biologics.

scholarly journals Air-Bubble Induced Mixing: A Fluidic Mixer Chip

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 195 ◽  
Author(s):  
Xiaoyu Jia ◽  
Bingchen Che ◽  
Guangyin Jing ◽  
Ce Zhang
Keyword(s):  
Bulk Solution ◽  
Liquid Volume ◽  
Mixing Efficiency ◽  
Flow Profile ◽  
Air Bubbles ◽  
Complex Flow ◽  
Air Bubble ◽  
Potential Applications ◽  
Unique Approach ◽  
Medical Analysis

In this study, we report the design and fabrication of a novel fluidic mixer. As proof-of-concept, the laminar flow in the main channel is firstly filled with small air-bubbles, which act as active stirrers inducing chaotic convective turbulent flow, and thus enhance the solutes mixing even at a low input flow rate. To further increase mixing efficiency, a design of neck constriction is included, which changes the relative positions of the inclusion bubbles significantly. The redistribution of liquid volume among bubbles then causes complex flow profile, which further enhances mixing. This work demonstrates a unique approach of utilizing air bubbles to facilitate mixing in bulk solution, which can find the potential applications in microfluidics, fast medical analysis, and biochemical synthesis.

Detailed numerical simulation and experimental investigation on micromixers with serpentine Koch fractal microchannels

2021 ◽  
pp. 2150228
Author(s):  
Yue Tian ◽  
Xueye Chen ◽  
Xiangwei Zeng ◽  
Xiangyang Wang ◽  
Xingxing Yu ◽  
...  
Keyword(s):  
Cross Section ◽  
Molecular Diffusion ◽  
Continuous Optimization ◽  
Fluid Mixing ◽  
Mixing Efficiency ◽  
Channel Spacing ◽  
Section Shape ◽  
Passive Micromixer ◽  
Koch Fractal ◽  
Fractal Number

Micromixer is a kind of microfluidic chip for fast mixing and analysis. Mixing in a micromixer is usually a micron scale. At low Reynolds number, the fluid in the channel is laminar flow, which mainly depends on molecular diffusion as the main mixing mode. Fluid mixing in microchannels is very difficult, especially when the viscosity of the fluid is high. In this paper, we design a novel passive micromixer. The effects of fractal number, Koch fractal channel spacing, microchannel depth and cross-section shape on mixing efficiency were studied. Through a large number of numerical simulations, we continue to optimize the structure of the micromixer and improve the mixing efficiency. Finally, through the continuous optimization of the structure of the micromixer, the mixing efficiency of the micromixer can reach more than 95%.

Evaluation of Fluid Behaviour and Mixing Efficiency in Predefined Serpentine Micro-Fracture System

2013 ◽  
Author(s):  
Gorakh Pawar ◽  
Ilija Miskovic ◽  
Manjunath Basavarajappa
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Hydraulic Fracturing ◽  
Oil And Gas ◽  
Rapid Expansion ◽  
Fluid Mixing ◽  
Mixing Efficiency ◽  
Fracturing Fluid ◽  
Hydraulic Fracturing Fluid ◽  
Geologic Media

Scientific research and development in the field of microfluidics and nanofluidics technology has witnessed a rapid expansion in recent years. Microfluidic and nanofluidic systems are finding increasing application in wide spectrum of biomedical and engineering fields, including oil and gas technology. Fluid flow characterization in porous geologic media is an important factor for predicting and improving oil and gas recovery. By developing understanding about the propagation of hydraulic fracturing fluid constituents in irregular micro- and nano-structures, and their multiphase interaction with reservoir fluids (e.g. mixing of supercritical CO2 with oil or gas) we can significantly improve efficiency of the current oil and gas (O&G) extraction process and reduce associated environmental impacts. In present paper, mixing of hydraulic fracturing fluid constituents in three dimensional serpentine microchannel system is simulated in CFD environment and results are used to evaluate mixing efficiency for different fracturing fluid compositions. In addition, pressure drop along the length of serpentine micro-channel is evaluated. Serpentine micro-channels considered in this study consist of periodic symmetrical and asymmetrical proppant particles, placed on both sides of the channel over the full length of the channel, to simulate realistic geometrical constraints usually seen in geological fractures. The fluid flow is characterized as a function of the proppant particle radius by varying size of adjacent proppant particles. Further, the flow is characterized by varying distance between adjacent proppant particles. Overall, this study will be primarily helpful to gain fundamental understanding of fracturing fluid mixing in micro-fractures, similar to real geologic media. In addition, this study will provide an insight into variations of fracturing fluid mixing efficiency, and pressure drop in micro-fracture systems as a function of geometry of the proppant particles at different flow rates.

NUMERICAL SIMULATION OF THREE-DIMENSIONAL PASSIVE MICROMIXER WITH VARIABLE-ANGLE GROOVES AND BAFFLES

2021 ◽  
pp. 2150037
Author(s):  
SIYUE XIONG ◽  
XUEYE CHEN
Keyword(s):  
Fluid Flow ◽  
Three Dimensional ◽  
Geometric Parameters ◽  
Mixing Efficiency ◽  
Flow State ◽  
Number Range ◽  
Variable Angle ◽  
Structure Changes ◽  
Chaotic Convection ◽  
Passive Micromixer

In this paper, we have studied the effect of variable-angle grooves and baffles on the mixing efficiency of the micromixer. In order to explore the influence on the micromixer with different types of grooves and baffles, we designed grooves and baffles with different geometric parameters and placed them in T-channels to interfere with fluid flow. We studied VAM30∘ (variable-angle grooves and baffles micromixer with an angle of 30∘) directions and distributions as well as their different groove depths and baffle heights affect the mixing performance. We tried to divide the grooves and baffles into five groups, and discussed the effects of staggered depth and height on mixing efficiency. The mixing efficiencies of micromixer in the Re (Reynolds number) range of 0.1–100 were calculated, and the fluid flow in the microchannel was analyzed. The simulation results show that VAM30∘ is more favorable for solution mixing. The mixing efficiency of the micromixer could reach 98.9% with the change of different geometric parameters. This is because when the structure changes, the flow state of the fluid is improved, which is conducive to lengthening the residence time of the fluid in the channel. With the increase of Re, it is also conducive to enhancing the chaotic convection and improving the mixing efficiency.

scholarly journals Selective Transport of Airborne Microparticles Through Micro-channels Under Microgravity

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Monia Makhoul ◽  
Philippe Beltrame
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Bifurcation Analysis ◽  
Metal Particles ◽  
Microgravity Environment ◽  
Ratchet Effect ◽  
Selective Transport ◽  
Microgravity Experiments ◽  
Particle Drift ◽  
Micro Channels

AbstractThis paper analyzes the possibility of obtaining the selective transport of microparticles suspended in air in a microgravity environment through modulated channels without net displacement of air. Using numerical simulation and bifurcation analysis tools, we show the existence of intermittent particle drift under the Stokes assumption of the fluid flow. The particle transport can be selective and the direction of transport is controlled only by the kind of pumping used. The selective transport is interpreted as a deterministic ratchet effect due to spatial variations in the flow and the particle drag. This ratchet phenomenon could be applied to the selective transport of metal particles during the short duration of microgravity experiments.

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