Electroosmotic Mixing of Non-Newtonian Fluid in a Microchannel with Obstacles and Zeta Potential Heterogeneity

Mei, Lanju; Cui, Defu; Shen, Jiayue; Dutta, Diganta; Brown, William; Zhang, Lei; Dabipi, Ibibia

doi:10.3390/mi12040431

Cited by 14 publications

(8 citation statements)

References 38 publications

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“…Both arrangements show similar improvement in mixing efficiency; however, the asymmetric configuration of the surface potential shows a higher flow rate. Mei et al [24] investigated how zeta potential heterogeneity and obstruction affects the non-Newtonian fluid's mixing characteristics. They found that mixing efficiency improved as obstacle height and zeta potential increased.…”

Section: Introductionmentioning

confidence: 99%

Vortex‐assisted electroosmotic mixing of Carreau fluid in a microchannel

Mehta

Mondal

2023

Electrophoresis

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Pertaining to the mixing of the non‐Newtonian Carreau fluid under electrokinetic actuation inside a plane microchannel, we propose a new design of micromixer that involves inserting a two‐part cylinder bearing zeta potential of the same sign but different magnitude in the upstream and downstream directions. We numerically solve the transport equations to predict the underlying mixing characteristics. We demonstrate that a substantial momentum difference between the microchannel's plane wall and cylinder leads to the development of a vortex in the flow pathway, which in turn, enhances mixing substantially. As shown, for a fluid having a highly shear‐thinning nature, the vortex‐assisted convection mixing strength increases with diffusivity of the candidate fluids. Moreover, it is shown that for the higher shear‐thinning nature of the candidate fluid, an increase in cylinder radius enhances mixing efficiency and flow rate simultaneously, resulting in a “quick and efficient” mixing condition. Additionally, the fluid rheology significantly alters the kinetics of shear‐induced binary aggregation. Our findings show that the shear‐induced aggregation characteristic time sharply increases with increasing shear‐thinning behavior of the fluid.

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Section: Introductionmentioning

confidence: 99%

Vortex‐assisted electroosmotic mixing of Carreau fluid in a microchannel

Mehta

Mondal

2023

Electrophoresis

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“…It was found that elasticity did not significantly change the flow of polyvinyl pyrrolidone and polyethylene oxide dilute non-Newtonian solutions (in comparison with Newtonian solution). Mei et al (2021) investigated the EO micro-mixing through a microchannel with obstacles on the wall. Their results showed that by increasing the zeta potential of the obstacle surface, mixing efficiency would be improved.…”

Section: Introductionmentioning

confidence: 99%

Transient heat transfer and electro-osmotic flow of Carreau–Yasuda non-Newtonian fluid through a rectangular microchannel

Ghorbani

Emamian²,

Delouei³

et al. 2023

HFF

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Purpose The purpose of this study is to investigate heat transfer and electrokinetic non-Newtonian flow in a rectangular microchannel in the developed and transient states. Design/methodology/approach The Carreau–Yasuda model was considered to capture the non-Newtonian behavior of the fluid. The dimensionless forms of governing equations, including the continuity equation for the Carreau–Yasuda fluid, are numerically solved by considering the volumetric force term of electric current (DC). Findings The impact of pertinent parameters such as electrokinetic diameter (R), Brinkman number and Peclet number is examined graphically. It is observed that for increasing R, the bulk velocity decreases. The velocity of the bulk fluid reaches from the minimum to the maximum state across the microchannel over time. At the electrokinetic diameter of 400, the maximum velocity was obtained. Temperature graphs are plotted with changes in the various Brinkman number (0.1 < Br < 0.7) at different times, and local Nusselt are compared against changes in the Peclet number (0.1 < ℘e < 0.5). The results of this study show that by increasing the Brinkman number from 0.25 to 0.7, the temperature along the microchannel doubles. It was observed that increasing the Peclet number from 0.3 to 0.5 leads to 200% increment of the Nusselt number along the microchannel in some areas along the microchannel. The maximum temperature occurs at Brinkman number of 0.7 and the maximum value of the local Nusselt number is related to Peclet number 0.5. Over time in the transient mode, the Nusselt number also decreases along the microchannel. By the increasing of time, the temperature increases at given value of Brinkman, which is insignificant at Brinkman number of 0.1. The simulation results have been verified by Newtonian and non-Newtonian flows with adequate accuracy. Originality/value This study contributes to discovering the effects of transient flow of electroosmotic flow for non-Newtonian Carreau–Yasuda fluid and transient heat transfer through rectangular microchannel. To the authors’ knowledge, the said investigation is yet not available in existing literature.

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“…The wal zeta-potential is considered negative for the heterogeneity segment, so there is positiv zeta-potential everywhere except for the heterogeneity patch. Microchannels can be designed through proper heterogeneity arrangement on channel surfaces for mixing, pumping, or both [27,28]. Under such a circumstance, th numerical solution of electroosmotic flow in heterogeneous channels without using th Helmholtz-Smoluchowski (H-S) approximate model is time-consuming [29,30], and few studies have been done in this field.…”

Section: Introductionmentioning

confidence: 99%

“…The surface-to-volume ratio is high in microchannels due to the small length scale so surface phenomena, useless in large-scale flows, are crucial in such microfluidic de vices. One of these surface phenomena playing an essential role in microfluidics is th Microchannels can be designed through proper heterogeneity arrangement on channel surfaces for mixing, pumping, or both [27,28]. Under such a circumstance, the numerical solution of electroosmotic flow in heterogeneous channels without using the Helmholtz-Smoluchowski (H-S) approximate model is time-consuming [29,30], and few studies have been done in this field.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of the Heterogeneity Effect on Electroosmotic Micromixers Based on the Standard Deviation of Concentration and Mixing Entropy Index

et al. 2021

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One approach to achieve a homogeneous mixture in microfluidic systems in the quickest time and shortest possible length is to employ electroosmotic flow characteristics with heterogeneous surface properties. Mixing using electroosmotic flow inside microchannels with homogeneous walls is done primarily under the influence of molecular diffusion, which is not strong enough to mix the fluids thoroughly. However, surface chemistry technology can help create desired patterns on microchannel walls to generate significant rotational currents and improve mixing efficiency remarkably. This study analyzes the function of a heterogeneous zeta-potential patch located on a microchannel wall in creating mixing inside a microchannel affected by electroosmotic flow and determines the optimal length to achieve the desired mixing rate. The approximate Helmholtz–Smoluchowski model is suggested to reduce computational costs and simplify the solving process. The results show that the heterogeneity length and location of the zeta-potential patch affect the final mixing proficiency. It was also observed that the slip coefficient on the wall has a more significant effect than the Reynolds number change on improving the mixing efficiency of electroosmotic micromixers, benefiting the heterogeneous distribution of zeta-potential. In addition, using a channel with a heterogeneous zeta-potential patch covered by a slip surface did not lead to an adequate mixing in low Reynolds numbers. Therefore, a homogeneous channel without any heterogeneity would be a priority in such a range of Reynolds numbers. However, increasing the Reynolds number and the presence of a slip coefficient on the heterogeneous channel wall enhances the mixing efficiency relative to the homogeneous one. It should be noted, though, that increasing the slip coefficient will make the mixing efficiency decrease sharply in any situation, especially in high Reynolds numbers.

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Electroosmotic Mixing of Non-Newtonian Fluid in a Microchannel with Obstacles and Zeta Potential Heterogeneity

Cited by 14 publications

References 38 publications

Vortex‐assisted electroosmotic mixing of Carreau fluid in a microchannel

Vortex‐assisted electroosmotic mixing of Carreau fluid in a microchannel

Transient heat transfer and electro-osmotic flow of Carreau–Yasuda non-Newtonian fluid through a rectangular microchannel

Numerical Analysis of the Heterogeneity Effect on Electroosmotic Micromixers Based on the Standard Deviation of Concentration and Mixing Entropy Index

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