Electrokinetically driven fluidic transport of power-law fluids in rectangular microchannels

Vakili, Mohammad Ali; Sadeghi, Arman; Saidi, Mohammad Hassan; Mozafari, A.

doi:10.1016/j.colsurfa.2012.07.030

Cited by 43 publications

(25 citation statements)

References 28 publications

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“…Figure 5 represents the cross-stream concentration profiles at different values of the flow behavior index between 0.6 and 1.2. In accordance with the numerical results reported by Vakili et al (2012), increasing the flow behavior index will lead to a decrease in the electroosmotic velocity; this, in turn, gives rise to an increase in crossstream diffusion effects. The ultimate effect of increasing n is to get more uniform concentration profiles, as observed in Fig.…”

Section: Resultssupporting

confidence: 87%

A depthwise averaging solution for cross-stream diffusion in a Y-micromixer by considering thick electrical double layers and nonlinear rheology

Yazdi

Sadeghi

Saidi

2015

Microfluid Nanofluid

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List of symbolsFlow consistency index (Pas n ) n Flow behavior index n 0 Ion density at neutral conditions (m −3 )Axial coordinate of moving reference frame (m) Z Valence number of ions in solutionGreek symbols α Channel aspect ratio (=W/H) δDimensionless thickness of diffusion layer εFluidEffective viscosity (Pas)Abstract Both nonlinear rheology and finite EDL thickness effects on the mixing process in an electroosmotically actuated Y-sensor are being investigated in this paper, utilizing a depthwise averaging method based on the Taylor dispersion theory. The fluid rheological behavior is assumed to obey the power-law viscosity model. Analytical solutions are obtained assuming a large channel width to depth ratio for which a 1-D profile can efficiently describe the velocity distribution. Full numerical simulations are also performed to determine the applicability range of the analytical model, revealing that it is able to provide accurate results for channel aspect ratios of ten and higher and quite acceptable results for smaller aspect ratios down to four. The model is then used for a complete parametric study to determine the effects of the governing parameters on the mixing performance. It is observed that utilizing a fluid with a higher flow behavior index gives rise to a smaller mixing length. Moreover, whereas a larger EDL thickness is accompanied by an improved mixing efficiency, the opposite is true for the channel aspect ratio. The effective diffusivity is also found to be an increasing function of the EDL extent and a decreasing function of the flow behavior index.

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Section: Resultssupporting

confidence: 87%

A depthwise averaging solution for cross-stream diffusion in a Y-micromixer by considering thick electrical double layers and nonlinear rheology

Yazdi

Sadeghi

Saidi

2015

Microfluid Nanofluid

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“…They showed that dimensionless mean velocity (and electrical zeta potential) is elevated with channel aspect ratio and the dimensionless Debye-Hückel parameter but depressed with rheological power law index. Chakraborty and Paul [27] analyzed the collective effects of electrical and magnetic forces in micro-channel flow control. They simulated the electric double layer (EDL) effects using the classical Poisson-Boltzmann equation, and found that volumetric flow rates are significantly increased with comparatively weak magnetic field, whereas with stronger magnetic fields, significant volumetric forces can oppose and inhibit flow rate augmentation.…”

Section: Introductionmentioning

confidence: 99%

Transverse magnetic field driven modification in unsteady peristaltic transport with electrical double layer effects

Tripathi

Bhushan

Bég

2016

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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The influence of transverse magnetic field on time-dependent peristaltic transport of electrically-conducting fluids through a microchannel under an applied external electric field with induced electric field effect is considered, based on lubrication theory approximations.The electrohydrodynamic (EHD) problem is also simplified under the Debye linearization.Closed-form solutions for the linearized dimensionless boundary value problem are derived.With increasing Hartmann number, the formation of bolus in the regime (associated with trapping) is inhibited up to a critical value of magnetic field. Flow rate, axial velocity and local wall shear stress are strongly decreased with greater Hartmann number whereas pressure difference is enhanced with higher Hartmann number at low time values but reduced with greater elapse in time. With greater electro-osmotic parameter (i.e. smaller Debye length), maximum time-averaged flow rate is enhanced, whereas the axial velocity is reduced. An increase in electrical field parameter (i.e. maximum electro-osmotic velocity) causes an increase in maximum time-averaged flow rate. The simulations find applications in electromagnetic peristaltic micro-pumps in medical engineering and also "smart" fluid pumping systems in nuclear and aerospace industries.

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“…(5) and (13) are numerically solved successively by applying a finite-difference procedure for non-uniform distribution of grid points throughout the computational domain. The procedure is quite identical to the method adopted by Vakili et al [12] and the details are not presented here for the sake of brevity. To ensure the gridindependency of the results, an extensive analysis was performed, revealing that 100 grid points in both z and y directions are sufficient to provide grid-independent results.…”

Section: Resultsmentioning

confidence: 98%

“…(9) and expanding the resultant terms and computing e  in accordance with Eq. (1), the momentum equation in dimensionless form can be written as , , A y z u are non-dimensional functions obtained as [12]  …”

Section: Velocity Distributionmentioning

confidence: 99%

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Steric effects on electrokinetic flow of non-linear biofluids

Yazdi

Sadeghi

Saidi

2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Electrokinetically driven fluidic transport of power-law fluids in rectangular microchannels

Cited by 43 publications

References 28 publications

A depthwise averaging solution for cross-stream diffusion in a Y-micromixer by considering thick electrical double layers and nonlinear rheology

A depthwise averaging solution for cross-stream diffusion in a Y-micromixer by considering thick electrical double layers and nonlinear rheology

Transverse magnetic field driven modification in unsteady peristaltic transport with electrical double layer effects

Steric effects on electrokinetic flow of non-linear biofluids

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