Streaming Potential and Electroosmotic Flow in Heterogeneous Circular Microchannels with Nonuniform Zeta Potentials:  Requirements of Flow Rate and Current Continuities

Langmuir ◽  
2004 ◽  
Vol 20 (10) ◽  
pp. 3863-3871 ◽  
Author(s):  
Jun Yang ◽  
J. H. Masliyah ◽  
Daniel Y. Kwok
Keyword(s):  
Flow Rate ◽  
Electroosmotic Flow ◽  
Streaming Potential ◽  
Zeta Potentials ◽  
Circular Microchannels

scholarly journals Electroosmotic Flow of Non-Newtonian Fluid in Porous Polymer Membrane at High Zeta Potentials

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1046
Author(s):  
Shuyan Deng ◽  
Yukun Zeng ◽  
Mingying Li ◽  
Cuixiang Liang
Keyword(s):  
Zeta Potential ◽  
Newtonian Fluid ◽  
Flow Rate ◽  
Applied Voltage ◽  
Electroosmotic Flow ◽  
Polymer Membrane ◽  
Porous Polymer ◽  
Total Flow ◽  
Total Flow Rate ◽  
Zeta Potentials

To help in the efficient design of fluid flow in electroosmotic pumps, electroosmotic flow of non-Newtonian fluid through porous polymer membrane at high zeta potentials is studied by mainly evaluating the total flow rate at different physical parameters. Non-Newtonian fluid is represented by the power-law model and the porous polymer membrane is considered as arrays of straight cylindrical pores. The electroosmotic flow of non-Newtonian fluid through a single pore is studied by solving the complete Poisson–Boltzmann equation and the modified Cauchy momentum equation. Then assuming the pore size distribution on porous polymer membrane obeys Gaussian distribution, the performance of electroosmotic pump operating non-Newtonian fluid is evaluated by computing the total flow rate of electroosmotic flow through porous polymer membrane as a function of flow behavior index, geometric parameters of porous membrane, electrolyte concentration, applied voltage, and zeta potential. It is found that enhancing zeta potential and bulk concentration rather than the applied voltage can also significantly improve the total flow rate in porous polymer membrane, especially in the case of shear thinning fluid.

Analysis of a Viscoelastic Fluid Flow in a Microchannel With Asymmetric Zeta Potentials Under a Combination of Electroosmotic and Magnetohydrodynamic Driven Forces

2014 ◽  
Author(s):  
Juan P. Escandón ◽  
Oscar E. Bautista ◽  
Federico Méndez
Keyword(s):  
Fluid Flow ◽  
Electric Fields ◽  
Viscoelastic Fluid ◽  
Flow Rate ◽  
Electroosmotic Flow ◽  
Future Application ◽  
Buffer Solution ◽  
Viscoelastic Parameter ◽  
Zeta Potentials ◽  
Fluid Field

In this paper an analytical solution to describe the velocity profiles and flow rate of combined electroosmotic and magnetohydrodynamic flows in a microchannel is obtained. A fully-developed flow is considered and the fluid obeys a constitutive relation based in a simplified Phan-Thien-Tanner model. Asymmetric boundary conditions with different zeta potentials at the walls are specified to provide a perturbation to the fluid flow. The effect of the dimensionless parameters on the flow field as viscoelastic parameter, the Hartmann number, the ratio of applied electric fields on the fluid field and the ratio of the wall zeta potentials is predicted. The analysis permits to establish the conditions for which the flow rate is increased respect to a purely electroosmotic flow, therefore, in the limit of small Hartmann numbers and low electrical conductivity in the buffer solution correspond to the range where the electric and magnetic effects can be used to move a charged solution in the flow control and sample handling in biomedical and chemical analysis. In addition, we determine the conditions that must be met to prevent the undesirable lateral electroosmotic flow, which is present in this kind of applications. Finally, the combined effect of asymmetric zeta potentials and electro-magnetic fields on viscoelastic fluid flows in microchannels is discussed as future application of mixed in microfluidics devices.

Measurement and Modeling of Condensation Heat Transfer Coefficients in Circular Microchannels

2006 ◽  
Vol 128 (10) ◽  
pp. 1050-1059 ◽  
Author(s):  
Todd M. Bandhauer ◽  
Akhil Agarwal ◽  
Srinivas Garimella
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Heat Transfer Model ◽  
Condensation Heat Transfer ◽  
Low Flow ◽  
Transfer Model ◽  
Shear Stresses ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Circular Microchannels

A model for predicting heat transfer during condensation of refrigerant R134a in horizontal microchannels is presented. The thermal amplification technique is used to measure condensation heat transfer coefficients accurately over small increments of refrigerant quality across the vapor-liquid dome (0<x<1). A combination of a high flow rate closed loop primary coolant and a low flow rate open loop secondary coolant ensures the accurate measurement of the small heat duties in these microchannels and the deduction of condensation heat transfer coefficients from measured UA values. Measurements were conducted for three circular microchannels (0.506<Dh<1.524mm) over the mass flux range 150<G<750kg∕m2s. Results from previous work by the authors on condensation flow mechanisms in microchannel geometries were used to interpret the results based on the applicable flow regimes. The heat transfer model is based on the approach originally developed by Traviss, D. P., Rohsenow, W. M., and Baron, A. B., 1973, “Forced-Convection Condensation Inside Tubes: A Heat Transfer Equation For Condenser Design,” ASHRAE Trans., 79(1), pp. 157–165 and Moser, K. W., Webb, R. L., and Na, B., 1998, “A New Equivalent Reynolds Number Model for Condensation in Smooth Tubes,” ASME, J. Heat Transfer, 120(2), pp. 410–417. The multiple-flow-regime model of Garimella, S., Agarwal, A., and Killion, J. D., 2005, “Condensation Pressure Drop in Circular Microchannels,” Heat Transfer Eng., 26(3), pp. 1–8 for predicting condensation pressure drops in microchannels is used to predict the pertinent interfacial shear stresses required in this heat transfer model. The resulting heat transfer model predicts 86% of the data within ±20%.

Electroosmotic Flow in Hydrophobic Microchannels of General Cross Section

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Morteza Sadeghi ◽  
Arman Sadeghi ◽  
Mohammad Hassan Saidi
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Electroosmotic Flow ◽  
Slip Length ◽  
Debye Length ◽  
Surface Hydrophobicity ◽  
Double Layers ◽  
Slip Conditions ◽  
Wall Boundary Conditions ◽  
Electroosmotic Velocity

Adopting the Navier slip conditions, we analyze the fully developed electroosmotic flow in hydrophobic microducts of general cross section under the Debye–Hückel approximation. The method of analysis includes series solutions which their coefficients are obtained by applying the wall boundary conditions using the least-squares matching method. Although the procedure is general enough to be applied to almost any arbitrary cross section, eight microgeometries including trapezoidal, double-trapezoidal, isosceles triangular, rhombic, elliptical, semi-elliptical, rectangular, and isotropically etched profiles are selected for presentation. We find that the flow rate is a linear increasing function of the slip length with thinner electric double layers (EDLs) providing higher slip effects. We also discover that, unlike the no-slip conditions, there is not a limit for the electroosmotic velocity when EDL extent is reduced. In fact, utilizing an analysis valid for very thin EDLs, it is shown that the maximum electroosmotic velocity in the presence of surface hydrophobicity is by a factor of slip length to Debye length higher than the Helmholtz–Smoluchowski velocity. This approximate procedure also provides an expression for the flow rate which is almost exact when the ratio of the channel hydraulic diameter to the Debye length is equal to or higher than 50.

Viscoelectric Effect on the Electroosmotic Flow in Nanochannels With Heterogeneous Zeta Potentials

2018 ◽  
Author(s):  
Edson M. Jimenez ◽  
Federico Méndez ◽  
Juan P. Escandón
Keyword(s):  
Electroosmotic Flow ◽  
Fluid Velocity ◽  
Volumetric Flow Rate ◽  
Mass Conservation ◽  
Double Layers ◽  
Fluid Viscosity ◽  
Governing Equations ◽  
Flat Plates ◽  
Zeta Potentials ◽  
Poisson Boltzmann

In the present work, we realize a study about the influence of viscoelectric effect on the electroosmotic flow of Newtonian fluids in nanochannels formed by two parallel flat plates. In the problem, the channel walls have heterogeneous zeta potentials which follow a sinusoidal distribution; moreover, viscoelectric effects appear into the electric double layers when high zeta potentials are considered at the channel walls, modifying the fluid viscosity and the fluid velocity. To find the solution of flow field, the modified Poisson-Boltzmann, mass conservation and momentum governing equations, are solved numerically. In the results, combined effects from the zeta potential heterogeneities and viscosity changes yields different kind of flow recirculations controlled by the dephasing angle, amplitude and number of waves of the heterogeneities at the walls. The viscoelectric effect produces a decrease in the magnitude of velocity profiles and volumetric flow rate when the high zeta potentials are magnified. Additionally, the heterogeneous zeta potentials at the walls generate an induced pressure on the flow. This investigation extend the knowledge of electroosmotic flows under field effects for future mixing applications.

Apparatus for determination of zeta potentials from streaming potentials

1963 ◽  
Vol 18 (6) ◽  
pp. 1263-1264 ◽  
Author(s):  
R. E. Beck ◽  
V. Mirkovitch ◽  
P. G. Andrus ◽  
R. I. Leininger
Keyword(s):  
Zeta Potential ◽  
Streaming Potential ◽  
Salt Solutions ◽  
Streaming Potentials ◽  
Zeta Potentials ◽  
Quartz Capillary ◽  
Flow Through

A system was developed to measure the streaming potential generated between the ends of a capillary by the flow of a fluid through the capillary. Zeta potential can be calculated from the streaming potential. Adequate sensitivity and reproducibility were achieved by making special electrodes: silver wires plated in KCl solution and embedded in agar, careful electrical shielding, and provision for reversal of flow through the capillary to minimize electrode errors. The apparatus was developed to measure streaming potentials generated by either RingerS's solution or blood in contact with capillaries made of different materials such as quartz, polyethylene, etc. An example of a determination using a quartz capillary is presented. interfaces; blood; salt solutions; glass; quartz Submitted on February 25, 1963

scholarly journals Analytical Solution for Heat Transfer in Electroosmotic Flow of a Carreau Fluid in a Wavy Microchannel

2019 ◽  
Vol 9 (20) ◽  
pp. 4359 ◽  
Author(s):  
Saima Noreen ◽  
Sadia Waheed ◽  
Abid Hussanan ◽  
Dianchen Lu
Keyword(s):  
Fluid Flow ◽  
Flow Pattern ◽  
Flow Rate ◽  
Electroosmotic Flow ◽  
Linear Problem ◽  
Perturbation Technique ◽  
Volumetric Flow Rate ◽  
Carreau Fluid ◽  
Long Wavelength ◽  
Wide Range

This article explores the heat and transport characteristics of electroosmotic flow augmented with peristaltic transport of incompressible Carreau fluid in a wavy microchannel. In order to determine the energy distribution, viscous dissipation is reckoned. Debye Hückel linearization and long wavelength assumptions are adopted. Resulting non-linear problem is analytically solved to examine the distribution and variation in velocity, temperature and volumetric flow rate within the Carreau fluid flow pattern through perturbation technique. This model is also suitable for a wide range of biological microfluidic applications and variation in velocity, temperature and volumetric flow rate within the Carreau fluid flow pattern.

Electroosmotic Flow Rate: A Semiempirical Approach

2000 ◽  
pp. 247-266 ◽  
Author(s):  
J. H. Chang ◽  
Z. Qiang ◽  
C. P. Huang ◽  
D. Cha
Keyword(s):  
Flow Rate ◽  
Electroosmotic Flow ◽  
Semiempirical Approach

Chaotic Electroosmotic Flow

2002 ◽  
Author(s):  
Shizhi Qian ◽  
Haim H. Bau
Keyword(s):  
Zeta Potential ◽  
Electroosmotic Flow ◽  
Analytic Solution ◽  
Microfluidic Devices ◽  
Chaotic Advection ◽  
Uniform Electric Field ◽  
Periodic Modulation ◽  
Chaotic Flows ◽  
Zeta Potentials ◽  
Series Convergence

Two dimensional, time-independent and time-dependent electroosmotic flows driven by a uniform electric field in rectangular cavities with uniform and non-uniform zeta potential distributions along the cavities’ walls are investigated theoretically. The time-independent flow fields are computed with the aid of Fourier series. The series’ convergence is accelerated so that highly accurate solutions are obtained with just a few (&lt;10) terms in the series. The analytic solution is used to compute flow patterns for various distributions of the zeta potential along the cavities’ boundaries. It is demonstrated that by time-wise periodic modulation of the zeta potentials, one can induce chaotic advection in the cavities. Such chaotic flows may be used to stir and mix fluids in microfluidic devices.

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