An Approximate Analytical Solution for Electro-Osmotic Flow of Power-Law Fluids in a Planar Microchannel

Sadeghi, Arman; Fattahi, Moslem; Saidi, Mohammad Hassan

doi:10.1115/1.4003968

Cited by 38 publications

(7 citation statements)

References 28 publications

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“…Pure EOF in this case has a linear velocity profile, and the stress is the constant c given by Eq. (19). In the case of symmetry 1 = 2 , the pure EOF has a plug flow profile, and c = 0.…”

Section: Flat and Uniformly Charged Walls But With Unequal Potentialsmentioning

confidence: 95%

Electroosmotic flow of a power-law fluid through an asymmetrical slit microchannel with gradually varying wall shape and wall potential

Cheng

2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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h i g h l i g h t s• Non-parallel electroosmotic flow of power-law fluid in a microchannel.• Lubrication theory for slowly varying channel height and wall potential.• Linear superposition of forces invalidated by asymmetry of channel.• Nonlinear interaction between wall undulation and wall charge modulation.• Flow-rate sensitive to phase shift of wall patterns and power-law index. g r a p h i c a l a b s t r a c t a b s t r a c tThis study aims to investigate electroosmotic flow of a power-law fluid through a slit channel with walls asymmetrically patterned with periodic variations in shape and zeta potential. On taking into account the near-wall depletion layer, the present problem is simplified on the basis of the lubrication approximation, and through the use of the Helmholtz-Smoluchowski slip boundary condition. Nonlinear equations are to be solved for two unknown functions of axial dependence, one being the induced pressure gradient, and another being an undetermined stress component. An efficient numerical scheme is devised in this work to solve the nonlinear problem. Results are generated to check whether the principle of linear superposition of forces, for electrokinetic flow of a non-Newtonian fluid in the presence of a Newtonian depletion layer, is still applicable to flow in an asymmetric channel. It is also found that phase shifts between the geometrical and electric potential patterns on the two walls may lead to qualitatively disparate effects, depending on the power-law behavior index of the fluid and the applied pressure gradient.

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“…Pure EOF in this case has a linear velocity profile, and the stress is the constant c given by Eq. (19). In the case of symmetry 1 = 2 , the pure EOF has a plug flow profile, and c = 0.…”

Section: Flat and Uniformly Charged Walls But With Unequal Potentialsmentioning

confidence: 95%

Electroosmotic flow of a power-law fluid through an asymmetrical slit microchannel with gradually varying wall shape and wall potential

Cheng

2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…where ρ e denotes net electric charge density, ò is the permittivity of the medium. The total electric potential Φ is given by the linear superposition of externally applied potential f ′ and the EDL potential ψ ′ -under the following conditions: (i) the Debye thickness is small compared with the channel diameter or height and (ii) the constant surface charge is assumed to be small (Sadeghi et al 2011, Ramos et al 2017. The electrical potential can be written as…”

Section: Electrical Potential Distributionmentioning

confidence: 99%

Electro-osmotic flow and heat transfer in a slowly varying asymmetric micro-channel with Joule heating effects

Mondal¹,

Shit²

2018

Fluid Dyn. Res.

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An analysis has been made to investigate the heat transfer characteristics of electro-osmotic flow (EOF) in a non-uniform micro-channel whose walls are varying sinusoidally. The EOF is driven by the combined influence of pressure gradient and axially imposed electric field. The energy equation accounts for viscous dissipation and the Joule heating effects. The effects of slip velocity due to hydrophobic interactions at the fluid-solid interface and thermal slip (temperature jump factor) are taken into consideration. The velocity and temperature fields are obtained analytically and their numerical results have been estimated for a given set of parameters. The Nusselt number and skinfriction coefficient at the wall of the channel are furthermore derived. The results show that less pressure gradient is required to drive same amount of fluid for presence of higher electro-osmotic parameter. The velocity slip parameter has enhancing effect on axial velocity. The temperature jump factor assigned at the walls of the micro-channel has reducing effect on temperature. The study also reveals that the Joule heating parameter has controlling effect on the temperature distribution. We made a comparison for the validation of our results with the results of those available in the scientific literature and shows excellent agreement.

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“…Thus far, the power-law model has been the most chosen rheological model by various studies, analytical or numerical, on EO flow of non-Newtonian fluids. Examples include Chakraborty [1], Berli and Olivares [2], Zhao et al [3], Bharti et al [4], Olivares et al [5], Tang et al [6], Zhao and Yang [7][8][9], Berli [10], Vasu and De [11,12], Babaie et al [13], Hadigol et al [14], Sadeghi et al [15], Cho et al [16,17], Deng et al [18], Shamshiri et al [19], Vakili et al. [20], and Zhu et al [21].…”

Section: Introductionmentioning

confidence: 99%

Electroosmotic flow of a power-law fluid in a non-uniform microchannel

Cheng

2014

Journal of Non-Newtonian Fluid Mechanics

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An analytical model is presented for electrokinetic flow of a power-law fluid through a slit channel with gradually varying channel height and wall potential. With the nearwall depletion effect taken into account, the present model is based on the lubrication approximation and the use of the Helmholtz-Smoluchowski slip boundary condition. It is found that interaction between the wall undulation and the wall potential modulation, under the combined action of hydrodynamic and electric forcings, may give rise to a rich set of nonlinear behaviors for flow of a non-Newtonian fluid in the channel. In particular, the linear superposition of flow components due separately to the two forcings is found to work only for a strictly uniform channel; non-uniformity in channel height or wall potential distribution will spoil such linearity.

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An Approximate Analytical Solution for Electro-Osmotic Flow of Power-Law Fluids in a Planar Microchannel

Cited by 38 publications

References 28 publications

Electroosmotic flow of a power-law fluid through an asymmetrical slit microchannel with gradually varying wall shape and wall potential

Electroosmotic flow of a power-law fluid through an asymmetrical slit microchannel with gradually varying wall shape and wall potential

Electro-osmotic flow and heat transfer in a slowly varying asymmetric micro-channel with Joule heating effects

Electroosmotic flow of a power-law fluid in a non-uniform microchannel

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