Numerical study of mixing in wavy micromixers: comparison between raccoon and serpentine mixer

Mondal, Bappa; Mehta, Sumit Kumar; Patowari, Promod Kumar; Pati, Sukumar

doi:10.1016/j.cep.2018.12.011

Cited by 122 publications

(41 citation statements)

References 55 publications

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“…The general mixing efficiency evaluation is achieved by measuring the standard deviation of concentration profiles in the entirely mixed state described by Eq. 7 [46][47][48]:…”

Section: Mixing Efficiency Index (Mei)mentioning

confidence: 99%

Numerical analysis of a microfluidic mixer and the effects of different cross-sections and various input angles on its mixing performance

Farahinia

Zhang

2020

J Braz. Soc. Mech. Sci. Eng.

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Micromixers have better efficiency in terms of both the timescale of chemical kinetics and diffusive transport compared to the conventional macro-mixers. The mixing efficiency in micromixers is an important performance indicator in mixers. This paper presents a numerical study of how the design of a micromixer along with the design of the mixing process affects the mixing efficiency. Specifically, two different types of cross-sections of the channel in micromixers, namely circular and rectangular cross-sections, together with the inlet angle of the channel, were studied. The process parameters, such as the inlet velocity of fluids and diffusion coefficient, were studied as well. The result shows that the circular cross-section can sustain a large pressure difference without undergoing any remarkable distortion and deformation, and it can achieve better performance. The result further indicates that the inlet velocity and diffusion coefficient have significant effects on mixing efficiency; specifically, the low inlet velocity and high diffusion coefficient value can lead to a better mixing performance. However, different input angles alone could not make the mixing efficiency change noticeably. In other words, the mixing performance of such micromixers relies more on the inlet velocity and diffusion coefficient than on the fluid flow angle in the inlet. Keywords Micromixers • COMSOL multiphysics • Pressure drop • Input angles • Mixing efficiency • Cross-section List of symbols A Cross-sectional area (m 2) C Concentration of reagents (mol/m 3) D Diffusion coefficient (m 2 /s) F Force (N) f Mole fraction (-) j Diffusion (mol/s m 2) I Identity matrix (-) L Microchannel length (m) M i Mixing efficiency (%) R Change in concentration rate (mol/s m 3) U Velocity (m/s) Density (kg/m 3) Viscosity (Pa s) Standard deviation (-)

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“…The general mixing efficiency evaluation is achieved by measuring the standard deviation of concentration profiles in the entirely mixed state described by Eq. 7 [46][47][48]:…”

Section: Mixing Efficiency Index (Mei)mentioning

confidence: 99%

Numerical analysis of a microfluidic mixer and the effects of different cross-sections and various input angles on its mixing performance

Farahinia

Zhang

2020

J Braz. Soc. Mech. Sci. Eng.

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“…The channel structures of these micromixers are relatively simple. By contrast, external energy sources are not required for passive micromixers, but this type of micromixer generally needs to have a complicated channel structure [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ] or set obstacles [ 20 , 21 , 22 , 23 ] in the microchannel to disturb the laminar flow for solution mixing under a relatively high pressure generated by a syringe pump. The mixing efficiency of passive micromixers is high, but the sealing of a microfluidic chip under high pressure is a challenge.…”

Section: Introductionmentioning

confidence: 99%

Liquid Mixing Based on Electrokinetic Vortices Generated in a T-Type Microchannel

Wang

2021

Micromachines

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This article proposes a micromixer based on the vortices generated in a T-type microchannel with nonuniform but same polarity zeta potentials under a direct current (DC) electric field. The downstream section (modified section) of the outlet channel was designed with a smaller zeta potential than others (unmodified section). When a DC electric field is applied in the microchannel, the electrokinetic vortices will form under certain conditions and hence mix the solution. The numerical results show that the mixing performance is better when the channel width and the zeta potential ratio of the modified section to the unmodified section are smaller. Besides, the electrokinetic vortices formed in the microchannel are stronger under a larger length ratio of the modified section to the unmodified section of the outlet channel, and correspondingly, the mixing performance is better. The micromixer presented in the paper is quite simple in structure and has good potential applications in microfluidic devices.

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“…Generally, these methods can be divided into two categories: active methods and passive methods [4]. Passive methods usually utilize various geometries [5–17] of microchannels and different shapes of obstacles [18–23] or grooves [24–27] placed in microchannels to disturb the laminar flow for vortex formation. Passive methods do not need external energy sources, but the channels of such methods usually need to be designed with complex structures, thereby increasing the fabrication difficulty.…”

Section: Introductionmentioning

confidence: 99%

Electrokinetic‐vortex formation near a two‐part cylinder with same‐sign zeta potentials in a straight microchannel

2020

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Vortex formation near a two-part cylinder with zeta potentials of different values but the same sign under an external DC electric field is numerically investigated in this paper. The cylinder, inserted in a straight microchannel filled with an aqueous solution, is composed of an upstream part and a downstream part. When a DC electric field is applied in the channel, under certain conditions, the vortex will form near the cylinder due to the different velocities of electroosmotic flow generated on the cylinder surface. The numerical results reveal that the larger the velocity difference of electroosmotic flow generated on the two-part cylinder and the smaller the channel width, the more conducive to vortex formation in the channel. In addition, if the zeta potential ratios of cylinder downstream part to upstream part and channel wall to cylinder upstream part are unchanged, the DC electric field strength and the zeta potential value do not affect the pattern of vortices formed in the channel. This study provides a way for vortex formation in microchannels and has the potential application in microfluidic devices.

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Numerical study of mixing in wavy micromixers: comparison between raccoon and serpentine mixer

Cited by 122 publications

References 55 publications

Numerical analysis of a microfluidic mixer and the effects of different cross-sections and various input angles on its mixing performance

Numerical analysis of a microfluidic mixer and the effects of different cross-sections and various input angles on its mixing performance

Liquid Mixing Based on Electrokinetic Vortices Generated in a T-Type Microchannel

Electrokinetic‐vortex formation near a two‐part cylinder with same‐sign zeta potentials in a straight microchannel

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