Analytical Solution of Time-Periodic Electroosmotic Flow through Cylindrical Microchannel with Non-Uniform Surface Potential

Khan, Aminul Islam; Dutta, Prashanta

doi:10.3390/mi10080498

Cited by 9 publications

(10 citation statements)

References 35 publications

(45 reference statements)

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“…On the contrary, when is very large ( = 3000) , the near-wall liquid oscillates rapidly while the bulk fluid remains immobile; since there is not sufficient time for momentum to diffuse further into the remaining part of the fluid. These behaviors and trends are in agreement with the results of [35], e.g. with Fig.…”

Section: Potential and Velocity Fieldssupporting

confidence: 92%

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AC EOF in a rectangular microannulus

Moghadam

2019

SN Appl. Sci.

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Electrokinetic flow under an alternating current electric field is numerically studied in a rectangular microannulus whose inner and outer surfaces may have different zeta potentials. The main parameters that affect the shape of the flow field are electrokinetic diameter, dimensionless frequency, surface charge ratio, aspect ratio, and hydraulic diameter. An increase in the electrokinetic diameter leads to a decrease in the effective electric double layer thickness, while the reverse is true for the Poiseuille number, maximum velocity near the wall, and the flow rate. Very low-frequency flow exhibits lidlike velocity profiles; on the contrary, very high-frequency flow represents thin oscillating layers close to the walls and a nearly stationary bulk fluid. Within the limit of higher-than-one excitation frequencies, the response of the liquid inside the electric double layer to the time-periodic electric field is almost immediate, while the rest needs a finite time to follow the instantaneous changes in the applied electric field. Instantaneous one-or two-direction flow can be produced, depending on the relative sign of the surface charges. For a fixed value of the electrokinetic diameter, the Poiseuille number increases and the flow rate decreases as a result of an increase in the hydraulic diameter.

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Section: Potential and Velocity Fieldssupporting

confidence: 92%

“…It was shown that flow control has linear dependence on the value of the applied electric field. Khan and Dutta [35] analyzed EOF in a cylindrical microchannel for heterogeneous surface charges. They showed that several vortices are formed inside the channel with sinusoidal surface charge distribution.…”

Section: Introductionmentioning

confidence: 99%

AC EOF in a rectangular microannulus

Moghadam

2019

SN Appl. Sci.

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“…This transport method has been theoretically studied since many years ago in small channels with Newtonian fluids, as the early works carried out by Burgreen and Nakache [ 6 ] and Rice and Whitehead [ 7 ]. Since then and until now, the scientific community has continued studies on the electroosmotic flow behavior using Newtonian [ 8 , 9 , 10 , 11 , 12 ] and non-Newtonian fluids [ 13 , 14 , 15 , 16 , 17 , 18 , 19 ], addressing emerging issues regarding the rheology of the fluids and ionic concentrations, channel geometry, wall zeta potentials effects, boundary slip effects, among other topics, and their implications on the flow characteristics.…”

Section: Introductionmentioning

confidence: 99%

Start-Up Electroosmotic Flow of Multi-Layer Immiscible Maxwell Fluids in a Slit Microchannel

et al. 2020

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In this investigation, the transient electroosmotic flow of multi-layer immiscible viscoelastic fluids in a slit microchannel is studied. Through an appropriate combination of the momentum equation with the rheological model for Maxwell fluids, an hyperbolic partial differential equation is obtained and semi-analytically solved by using the Laplace transform method to describe the velocity field. In the solution process, different electrostatic conditions and electro-viscous stresses have to be considered in the liquid-liquid interfaces due to the transported fluids content buffer solutions based on symmetrical electrolytes. By adopting a dimensionless mathematical model for the governing and constitutive equations, certain dimensionless parameters that control the start-up of electroosmotic flow appear, as the viscosity ratios, dielectric permittivity ratios, the density ratios, the relaxation times, the electrokinetic parameters and the potential differences. In the results, it is shown that the velocity exhibits an oscillatory behavior in the transient regime as a consequence of the competition between the viscous and elastic forces; also, the flow field is affected by the electrostatic conditions at the liquid-liquid interfaces, producing steep velocity gradients, and finally, the time to reach the steady-state is strongly dependent on the relaxation times, viscosity ratios and the number of fluid layers.

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“…Microchannels are a fundamental part of microfluidic systems. A number of researches have been conducted to understand the mechanism of fluid flow and heat transfer characteristics in microchannels with circular [1,2,3], parallel plates [4,5,6], annular [7,8,9], rectangular [10,11,12,13,14,15] and trapezoidal [16,17,18] cross-sections. Compared with a circular duct, a better thermal efficiency can be found in an elliptical passage because the perimeter of an elliptical configuration is wider than the other for the same cross-sectional area [19].…”

Section: Introductionmentioning

confidence: 99%

Thermally Developing Flow and Heat Transfer in Elliptical Minichannels with Constant Wall Temperature

Duan

et al. 2019

Micromachines

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Laminar convective heat transfer of elliptical minichannels is investigated for hydrodynamically fully developed but thermal developing flow with no-slip condition. A three-dimensional numerical model is developed in different elliptical geometries with the aspect ratio varying from 0.2 to 1. The effect of Reynolds number (25 ≤ Re ≤ 2000) on the local Nusselt number is examined in detail. The results indicate that the local Nusselt number is a decreasing function of Reynolds number and it is sensitive to Reynolds number especially for Re less than 250. The effect of aspect ratio on local Nusselt number is small when compared with the effect of Reynolds number on local Nusselt number. The local Nusselt number is independent of cross-section geometry at the inlet. The maximum effect of aspect ratio on local Nusselt number arises at the transition section rather than the fully developed region. However, the non-dimensional thermal entrance length is a monotonic decreasing concave function of aspect ratio but a weak function of Reynolds number. Correlations for the local Nusselt number and the thermal developing length for elliptical channels are developed with good accuracy, which may provide guidance for design and optimization of elliptical minichannel heat sinks.

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Analytical Solution of Time-Periodic Electroosmotic Flow through Cylindrical Microchannel with Non-Uniform Surface Potential

Cited by 9 publications

References 35 publications

AC EOF in a rectangular microannulus

AC EOF in a rectangular microannulus

Start-Up Electroosmotic Flow of Multi-Layer Immiscible Maxwell Fluids in a Slit Microchannel

Thermally Developing Flow and Heat Transfer in Elliptical Minichannels with Constant Wall Temperature

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