Flow Structure and Mixing Efficiency of Viscous Fluids in Microchannel with a Striped Superhydrophobic Wall

Vagner, S. A.; Патлажан, С. А.

doi:10.1021/acs.langmuir.9b02884

Cited by 10 publications

(5 citation statements)

References 66 publications

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“…2017; Patlazhan & Vagner 2017; Arenas et al. 2019; Fairhall, Abderrahaman-Elena & García-Mayoral 2019; Schnitzer & Yariv 2019; Vagner & Patlazhan 2019; Landel et al. 2020; Nayak et al.…”

Section: Summary and Concluding Remarksmentioning

confidence: 99%

Poiseuille flow of a Bingham fluid in a channel with a superhydrophobic groovy wall

Rahmani

Taghavi

2022

J. Fluid Mech.

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Plane Poiseuille flow of a Bingham fluid in a channel armed with a superhydrophobic (SH) lower wall is analysed via a semi-analytical model, accompanied by complementary direct numerical simulations (DNS). The SH surface represents a groovy structure with air trapped inside its cavities. Therefore, the fluid adjacent to the wall undergoes stick–slip conditions. The model is developed based on introducing infinitesimal wall-induced perturbations into the motion equations, followed by Fourier series expansions, and solving the resulting equations as a boundary value problem. The Navier slip law accounts for the slip at the liquid/air interface (assuming the Cassie state). The presented analysis is fairly comprehensive, covering the creeping and inertial regimes for thick channels (via the semi-analytical and DNS solutions). The main dimensionless numbers are the Reynolds ( $Re$ ), Bingham ( $Bi$ ) and slip ( $b$ ) numbers, as well as the groove periodicity length ( $\ell$ ) and the slip area fraction ( $\varphi$ ). By increasing $Bi$ , the perturbation and slip velocity fields grow. As $Re$ increases, the perturbation and slip velocity fields become asymmetric. For certain flow parameters, an unyielded plug zone may appear on the SH wall liquid/air interface, while its formation is accelerated by inertial effects. The results classify the regimes of creeping and inertial flows via predicting the onset of the unyielded plug zone formation at the SH wall.

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“…2017; Patlazhan & Vagner 2017; Arenas et al. 2019; Fairhall, Abderrahaman-Elena & García-Mayoral 2019; Schnitzer & Yariv 2019; Vagner & Patlazhan 2019; Landel et al. 2020; Nayak et al.…”

Section: Summary and Concluding Remarksmentioning

confidence: 99%

Poiseuille flow of a Bingham fluid in a channel with a superhydrophobic groovy wall

Rahmani

Taghavi

2022

J. Fluid Mech.

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“…Such an analysis may be of interest for practical applications, such as passive mixing (Stroock et al. 2002 b ; Vagner & Patlazhan 2019) and particle fractionation and manipulation (Asmolov et al. 2015, 2018; Nizkaya et al.…”

Section: Flow Featuresmentioning

confidence: 99%

“…Such an analysis explores the direction where the flow slippage occurs on the patterned wall, thus, revealing the direction towards which the average shear force is applied to the patterned wall by the Bingham fluid. Such an analysis may be of interest for practical applications, such as passive mixing (Stroock et al 2002b;Vagner & Patlazhan 2019) and particle fractionation and manipulation (Asmolov et al 2015(Asmolov et al , 2018Nizkaya et al 2020) in channels with patterned walls, where the flow streamline structure near the patterned wall is important.…”

Section: Slip Anglementioning

confidence: 99%

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A comprehensive model for viscoplastic flows in channels with a patterned wall: longitudinal, transverse and oblique flows

Rahmani,

Taghavi

2024

J. Fluid Mech.

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We develop a comprehensive model for the creeping Poiseuille Bingham flow in channels equipped with a patterned wall, i.e. decorated with grooves or stripes that may represent a superhydrophobic (SH) or a chemically patterned (CP) surface, respectively, with longitudinal, transverse and oblique groove (stripe) orientations with respect to the applied pressure gradient. We rely on the Navier slip law to model the boundary condition on the slippery grooves. We develop semi-analytical, explicit-form and complementary computational fluid dynamics models, with solutions that have reasonable agreement. In contrast to its Newtonian analogue, a distinct solution for the oblique configuration, with an a priori unknown transform matrix, must be developed due to the viscoplastic nonlinear rheology. Our focus is to systematically analyse the effects of the Bingham number ( $B$ ), slip number ( $b$ ), groove periodicity length ( $\ell$ ), slip area fraction ( $\varphi$ ) and groove orientation angle ( $\theta$ ), on the slip velocities, effective slip length ( $\chi$ ), slip angle difference ( $\theta -s$ ), mixing index ( $I_M$ ), flow anisotropy and flow regimes. In particular, we demonstrate that, as $B$ increases, the maximum values of the shear component of $\chi$ , $\theta -s$ and $I_M$ occur progressively at smaller values of $\theta$ , compared with their Newtonian counterparts.

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“…Recent advancements in state-of-the-art technology have brought microfluidic devices/systems to the forefront in various fields, including medication delivery, chemical synthesis, biosensors, cell analysis, and medical diagnostics. − Typically, microfluidic systems/devices used in these applications are involved in an important functionality, i.e., the mixing of solutes/species with diffusion coefficient ∼ O (10 –10 –10 –12 m 2 /s). Pertaining to this value of the diffusion coefficient, the order of the diffusive Peclet number becomes ∼ O ( Pe ) ≫1, − even for the creeping flow regime and characteristic length scale in micron. − This order analysis suggests that convection, rather than molecular diffusion, seems to be the dominant mode of underlying solute mixing.…”

Section: Introductionmentioning

confidence: 99%

AC Electrothermal Effect Promotes Enhanced Solute Mixing in a Wavy Microchannel

Mehta,

Mondal

2023

Langmuir

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For liquids used in biological applications, a smaller diffusion coefficient results in a longer mixing time. We discuss, in this endeavor, the promising potential of the AC electrothermal (ACET) effect toward modulating enhanced mixing of electrolytic liquids with higher convective strength in a novel wavy micromixer. To this end, we develop a modeling framework and numerically solve the pertinent transport equations in a three-dimensional (3D) configuration numerically. By benchmarking the developed modeling framework with the experimental results available in this paradigm, we aptly demonstrate the maximum temperature rise, flow topology, species concentration field, and mixing efficiency in the proposed configuration for a set of parameters pertinent to this analysis. We find that the maximum temperature increase in the wavy micromixer, owing to the electrothermal effect, is less than 10 K even for the higher strength of the applied voltage, implying nondegradation of biological substances within the liquid sample. We report that the formation of significant lateral flow closer to the electrodes leads to a highly three-dimensional ACET flow field, which has a significant impact on the mixing efficiency for the range of diffusive Peclet numbers considered. We also report that the wave amplitude of the mixer, when intervening with the diffusive Peclet number, strongly impacts the mixing efficiency. As witnessed in this endeavor, for the smaller diffusive Peclet number, the mixing efficiency increases with amplitude, while the effect becomes the opposite for the higher Peclet number. The results of this study seem to provide an adequate basis for the design of a novel micromixer intended for enhanced solute mixing in realistic microfluidic applications.

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Flow Structure and Mixing Efficiency of Viscous Fluids in Microchannel with a Striped Superhydrophobic Wall

Cited by 10 publications

References 66 publications

Poiseuille flow of a Bingham fluid in a channel with a superhydrophobic groovy wall

Poiseuille flow of a Bingham fluid in a channel with a superhydrophobic groovy wall

A comprehensive model for viscoplastic flows in channels with a patterned wall: longitudinal, transverse and oblique flows

AC Electrothermal Effect Promotes Enhanced Solute Mixing in a Wavy Microchannel

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