Transient Electroosmotic Flow of Newtonian Fluids in a Microchannel With Heterogeneous Zeta Potentials at the Walls

2016 ◽  
Author(s):  
Juan P. Escandón ◽  
Eduardo G. Merino ◽  
Clara G. Hernández
Keyword(s):  
Electroosmotic Flow ◽  
Transient Flow ◽  
Transient Behavior ◽  
Velocity Profiles ◽  
Momentum Conservation ◽  
Newtonian Fluids ◽  
Zeta Potentials ◽  
Poisson Boltzmann ◽  
Sinusoidal Functions ◽  
Behavior Characteristics

This paper presents an analytical study of the transient electroosmotic flow for Newtonian fluids through a parallel flat plate microchannel with heterogeneous zeta potentials. The dimensionless mathematical model is based on the Poisson-Boltzmann, mass and momentum conservation governing equations together with the lubrication theory. The distribution of the zeta potentials at the walls obeys to a sinusoidal function, which includes dimensional parameters as Δζ that controls the magnitude and polarity of the zeta potentials, being capable to produce slanted velocity profiles and inverse flows. On the other hand, the combination of the phase angle between the sinusoidal functions of the zeta potentials ω, the dimensionless parameter of their amplitude Δζ, and the parameter that controls the frequency of the sinusoidal functions m, induce additional perturbations on the flow, which is directly related to the dimensionless pressure distribution and to the transient flow field. The transient behavior characteristics of the electroosmotic flow are discussed in terms of the zeta potential variations. It is demonstrated that the results for the transient electroosmotic flow, predict the influence of the main dimensionless parameters above mentioned on the velocity profiles and the streamlines. This work about the perturbations on the electroosmotic flow by heterogeneous zeta potentials, contributes to a better understanding of the transport phenomena in microfluidic devices for future mixing applications.

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.

scholarly journals Optimizing electroosmotic flow in an annulus from Debye Hückel approximation to Poisson–Boltzmann equation

RSC Advances ◽  
2017 ◽  
Vol 7 (12) ◽  
pp. 7274-7286 ◽  
Author(s):  
Gan-Jun Cen ◽  
Chien-Cheng Chang ◽  
Chang-Yi Wang
Keyword(s):  
Boltzmann Equation ◽  
Electroosmotic Flow ◽  
Zeta Potentials ◽  
Inner Radius ◽  
Poisson Boltzmann ◽  
Pumping Rates ◽  
Poisson Boltzmann Equation ◽  
Annular Tube

Optimal EO pumping rates on the plane of zeta potentials with distribution of the inner radius of annular tube.

Velocity Profiles and Unsteady Pipe Friction in Transient Flow

2000 ◽  
Vol 126 (4) ◽  
pp. 236-244 ◽  
Author(s):  
Bruno Brunone ◽  
Bryan W. Karney ◽  
Michele Mecarelli ◽  
Marco Ferrante
Keyword(s):  
Transient Flow ◽  
Velocity Profiles

Rapidly recovered transient flow resistance: a newly discovered property of blood

1987 ◽  
Vol 253 (4) ◽  
pp. H919-H926 ◽  
Author(s):  
D. E. McMillan ◽  
J. Strigberger ◽  
N. G. Utterback
Keyword(s):  
Shear Rate ◽  
Flow Resistance ◽  
Transient Flow ◽  
Transient Behavior ◽  
Fast Response ◽  
Sudden Onset ◽  
Stress Variation ◽  
Blood Flows ◽  
Erythrocyte Rigidity ◽  
Total Shear

Although blood flows in a pulsatile fashion, little consideration has been given in past studies to its instantaneous resistance to motion when onset and cessation of flow occur abruptly. Hemorheological studies have documented three kinds of blood flow properties. 1) Shear thinning is a fall in viscolity as shear rate rises. 2) Viscoelasticity is a transient shear stress variation due to elastic deformation of erythrocytes. Dilatancy is a viscoelasticity-modifying property attributed to high shear rate erythrocyte rigidity; viscoelasticity is prominent only at low shear rate. 3) Thixotropy is an initial extra flow resistance linked to developing orientation and disaggregation of erythrocytes. Thixotropy returns fully to blood over a period longer than 1 min. Measurements utilizing a fast response Couette viscometer have revealed an extra 10% transient flow resistance after a flow cessation shorter than that between heart beats. The rapidly recovered transient flow resistance has a temporal pattern similar to thixotropy. Its peak and duration are directly related to total shear strain (shear rate x time) over the 8-30 s-1 shear rate range studied. Transient behavior was essentially identical in analyses carried out using three different viscometer gaps. Numerical simulation to test the effect of the newly observed transient behavior on sudden onset tube flow shows that the developing pattern of pulsatile arterial flow can be affected by its presence.

Smearing of a Kick While Being Displaced From a Well

1991 ◽  
Vol 113 (3) ◽  
pp. 154-156
Author(s):  
M. Haciislamoglu ◽  
J. Langlinais
Keyword(s):  
Computer Model ◽  
Velocity Profiles ◽  
Newtonian Fluids ◽  
Well Control ◽  
Gas Kick

Well control operations while drilling with an oil-base mud can suffer several unexpected phenomena. One of these is the dispersion (smearing) of the gas in solution whenever a gas kick is being circulated from the well. If the gas influx has gone into solution, it is very important to predict the movement of this gas-contaminated mud as it is circulated from the well. A computer model of non-Newtonian fluids flowing in an annulus of any eccentricity has been developed with which to accurately model this dispersion. The movement of the gas-contaminated mud is predicted as a consequence of the velocity profiles established as the displacement of the annulus progresses.

Development of a Numerical Model for Single- and Two-Phase Flow Simulation in Perforated Porous Media

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Hamed Movahedi ◽  
Mehrdad Vasheghani Farahani ◽  
Mohsen Masihi
Keyword(s):  
Porous Media ◽  
Fluid Flow ◽  
Transient Flow ◽  
Accurate Determination ◽  
Flow Simulation ◽  
Velocity Profiles ◽  
Geometrical Parameters ◽  
Reservoir Properties ◽  
Two Phase ◽  
Phase Fluid

Abstract In this paper, we present a computational fluid dynamics (CFD) model to perform single- and two-phase fluid flow simulation on two- and three-dimensional perforated porous media with different perforation geometries. The finite volume method (FVM) has been employed to solve the equations governing the fluid flow through the porous media and obtain the pressure and velocity profiles. The volume of fluid (VOF) method has also been utilized for accurate determination of the volume occupied by each phase. The validity of the model has been achieved via comparing the simulation results with the available experimental data in the literature. The model was used to analyze the effect of perforation geometrical parameters (length and diameter), degree of heterogeneity, and also crushed zone properties (permeability and thickness) on the pressure and velocity profiles. The two-phase fluid flow around the perforation tunnel under the transient flow regime was also investigated by considering a constant mass flow boundary condition at the inlet. The developed model successfully predicted the pressure drop and resultant temperature changes for the system of air–water along clean and gravel-filled perforations under the steady-state conditions. The presented model in this study can be used as an efficient tool to design the most appropriate perforation strategy with respect to the well characteristics and reservoir properties.

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 (<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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