Electroosmotic flow and heat transfer in a heterogeneous circular microchannel

Azari, Milad; Sadeghi, Arman; Chakraborty, Suman

doi:10.1016/j.apm.2020.06.022

Cited by 27 publications

(11 citation statements)

References 47 publications

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“…Considering a steady and fully developed flow, the basic law of momentum conservation is mathematically expressed as (Azari, Sadeghi & Chakraborty 2020) Here, U is the axial velocity, P is the pressure and stands for the dynamic viscosity. In this study, the no-slip boundary condition is considered at the walls.…”

Section: Problem Formulationmentioning

confidence: 99%

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Unsteady convective–diffusive transport in semicircular microchannels with irreversible wall reaction

Azari

Sadeghi

2022

J. Fluid Mech.

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The unsteady dispersion of a solute band by a steady pressure-driven flow in a semicircular microchannel is theoretically studied via the generalized dispersion model. Considering an irreversible first-order reaction at the curved wall while assuming a no-flux boundary condition at the flat wall, analytical solutions are obtained for the exchange, convection and dispersion coefficients as well as the dimensionless forms of solute concentration and mean solute concentration. The solutions are obtained assuming an initial solute band of arbitrary cross-sectional shape and axial distribution and the results are presented for both circular and semicircular shapes with the uniform distribution being a special case of the latter. Besides the general solutions, special solutions are also derived for uniform velocity and no-reaction cases. In the following, the influences of the initial concentration distribution and the Damköhler number, a measure of the reaction rate, on the transport coefficients and the concentration distribution are investigated in depth. It is demonstrated that the combination of the initial concentration distribution and the Damköhler number specifies the variations of the transport coefficients in the short term but the Damköhler number is the only parameter dominating the long-term values: the exchange and convection coefficients are increasing functions of the Damköhler number whereas the opposite is true for the dispersion coefficient. Moreover, we show that, provided the solute injection is appropriately positioned and shaped, liquid-phase transportation with little dispersion is possible in typical microchannels utilizing semicircular geometry.

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Section: Problem Formulationmentioning

confidence: 99%

“…Considering a steady and fully developed flow, the basic law of momentum conservation is mathematically expressed as (Azari, Sadeghi & Chakraborty 2020) 1 R…”

Section: Velocity Distributionmentioning

confidence: 99%

Unsteady convective–diffusive transport in semicircular microchannels with irreversible wall reaction

Azari

Sadeghi

2022

J. Fluid Mech.

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“…In small channels, electroosmotic flow may also be deployed in chemical separation techniques, notably capillary electrophoresis. Several investigations of heat transfer in electro-osmotic flows have been reported [27,28]. Electroosmotic squeezing flows have also recently been studied by several investigators.…”

Section: Introductionmentioning

confidence: 99%

Electroosmotic modulated unsteady squeezing flow with temperature-dependent thermal conductivity, electric and magnetic field effects

Prakash¹,

Tripathi

Bég

et al. 2022

J. Phys.: Condens. Matter

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Modern lubrication systems are increasingly deploying smart (functional) materials. These respond to various external stimuli including electrical and magnetic fields, acoustics, light etc. Motivated by such developments, in the present article unsteady electro-magnetohydrodynamics (EMHD) squeezing flow and heat transfer in a smart ionic viscous fluid intercalated between parallel plates with zeta potential effects is examined. The proposed mathematical model of problem is formulated as a system of partial differential equations (continuity, momenta and energy). Viscous dissipation and variable thermal conductivity effects are included. Axial electrical distribution is also addressed. The governing equations are converted into ordinary differential equations via similarity transformations and then solved numerically with MATLAB software. The transport phenomena are scrutinized for both when the plates move apart or when they approach each other. Also, the impact of different parameters such squeezing number, variable thermal conductivity parameter, Prandtl number, Hartmann number, Eckert number, zeta potential parameter, electric field parameter and electroosmosis parameter on the axial velocity and fluid temperature are analyzed. For varied intensities of applied plate motion, the electro-viscous effects derived from electric double-capacity flow field distortions are thoroughly studied. It has been shown that the results from the current model differ significantly from those achieved by using a standard Poisson-Boltzmann equation model. Axial velocity acceleration is induced with negative squeeze number (plates approaching, S< 0) in comparison to that of positive squeeze number (plates separating, S>0). Velocity enhances with increasing electroosmosis parameter and zeta potential parameter. With rising values of zeta potential and electroosmosis parameter, there is a decrease in temperatures for U_e>0 for both approaching i. e. squeezing plates (S < 0) and separating (S >0) cases. The simulations provide novel insights into smart squeezing lubrication with thermal effects and also a solid benchmark for further computational fluid dynamics (CFD) investigations.

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“…According to their results, an increase of length enhances the performance of the vortex-generator fin. Azari et al [11] checked the heat exchange in a heterogeneous circular microchannel, the results show the maximum heat exchange rates are got when the boundary conditions are symmetrical. Darzi et al [12] have performed an experimental probing in a corrugated tube with nanofluid, they deduced that nanofluid with corrugated tubing could increase heat exchange by 330% compared to net liquid.…”

Section: Introductionmentioning

confidence: 99%

Thermal Performance Enhancement Using Absorber Tube with Inner Helical Axial Fins in a Parabolic Trough Solar Collector

et al. 2021

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In the present work, a parabolic trough solar (PTC) collector with inner helical axial fins as swirl generator or turbulator is considered and analyzed numerically. The three-dimensional numerical simulations have been done by finite volume method (FVM) using a commercial CFD code, ANSYS FLUENT 18.2. The spatial discretization of mass, momentum, energy equations, and turbulence kinetic energy has been obtained by a second-order upwind scheme. To compute gradients, Green-Gauss cell-based method has been employed. This work consists of two sections where, first, four various geometries are appraised, and in the following, the selected schematic of the collector from the previous part is selected, and four various pitches of inner helical fins including 250, 500, 750 and 1000 mm are studied. All the numerical results are obtained by utilizing the FVM. Results show that the thermal performance improvement by 23.1% could be achieved by using one of the proposed innovative parabolic trough solar collectors compare to the simple one. Additionally, the minimum and maximum thermal performance improvement (compare to the case without fins) belong to the case with P = 250 mm by 14.1% and, to the case with P = 1000 mm by 21.53%, respectively.

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Electroosmotic flow and heat transfer in a heterogeneous circular microchannel

Cited by 27 publications

References 47 publications

Unsteady convective–diffusive transport in semicircular microchannels with irreversible wall reaction

Unsteady convective–diffusive transport in semicircular microchannels with irreversible wall reaction

Electroosmotic modulated unsteady squeezing flow with temperature-dependent thermal conductivity, electric and magnetic field effects

Thermal Performance Enhancement Using Absorber Tube with Inner Helical Axial Fins in a Parabolic Trough Solar Collector

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