Thermodiffusive effect on the local Debye-length in an electroosmotic flow of a viscoelastic fluid in a slit microchannel

2022 ◽  
Vol 187 ◽  
pp. 122522
Author(s):  
A. Hernández ◽  
J. Arcos ◽  
J. Martínez-Trinidad ◽  
O. Bautista ◽  
S. Sánchez ◽  
...  
Keyword(s):  
Viscoelastic Fluid ◽  
Electroosmotic Flow ◽  
Debye Length

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.

scholarly journals Electroosmotic Flow of Viscoelastic Fluid in a Nanoslit

Micromachines ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 155 ◽  
Author(s):  
Lanju Mei ◽  
Hongna Zhang ◽  
Hongxia Meng ◽  
Shizhi Qian
Keyword(s):  
Viscoelastic Fluid ◽  
Electroosmotic Flow

Electroosmotic flow of viscoelastic fluid through a microchannel with slip-dependent zeta potential

2021 ◽  
Vol 33 (12) ◽  
pp. 123110
Author(s):  
Kasavajhula Naga Vasista ◽  
Sumit Kumar Mehta ◽  
Sukumar Pati ◽  
Sandip Sarkar
Keyword(s):  
Zeta Potential ◽  
Viscoelastic Fluid ◽  
Electroosmotic Flow

Similar Region in Electroosmotic Flow Rate for Newtonian and Non-Newtonian Fluids Using Dissipative Particle Dynamics (DPD)

2014 ◽  
Author(s):  
Ramin Zakeri ◽  
Eon Soo Lee
Keyword(s):  
Electroosmotic Flow ◽  
Flow Behavior ◽  
Dissipative Particle Dynamics ◽  
Debye Length ◽  
Particle Dynamics ◽  
Newtonian Fluids ◽  
Channel Height ◽  
Flow Rates ◽  
Power Law Fluids ◽  
Force Calculation

In this paper, analysis of electroosmotic flow in Newtonian and non Newtonian fluids in nanochannel with dissipative particle dynamics (DPD) method is presented and our results are validated with analytical solutions. Our aim is that which region or regions, based on the volumetric flow rates, in non-Newtonian fluids are similar with comparison to Newtonian ones in regards to various effective EOF parameters. For numerical simulation, the linearized Poisson Boltzmann for external force calculation is used and DPD method is applied for power law fluids to predict non-Newtonian fluids behavior in electroosmotic in various conditions such as different zeta potential, external electric fields, kh parameter (mainly Debye length and channel height), and flow behavior index. Based on the our results, for certain values of effective parameters, there are regions for volumetric flow rates which both Newtonian and non Newtonian electroosmotic flows have similar behavior while out of these regions, there are obviously significant differences and it is not possible to take Newtonian assumption for these regions. Based on our results validated with analytical solution, simplified assumption of taking non Newtonian fluid as Newtonians ones, in different EOF conditions in most cases, have a clearly inaccuracy and presented method can predict which EOF rates in both cases are correctly similar.

scholarly journals Electroosmotic Flow of Viscoelastic Fluid in a Nanochannel Connecting Two Reservoirs

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 747 ◽  
Author(s):  
Mei ◽  
Qian
Keyword(s):  
Constitutive Model ◽  
Viscoelastic Fluid ◽  
Flow Rate ◽  
Electroosmotic Flow ◽  
Double Layers ◽  
Ionic Conductance ◽  
Electrical Double Layers ◽  
Interconnect System ◽  
First Time ◽  
Thinning Effect

: Electroosmotic flow (EOF) of viscoelastic fluid with Linear Phan-Thien–Tanner (LPTT) constitutive model in a nanochannel connecting two reservoirs is numerically studied. For the first time, the influence of viscoelasticity on the EOF and the ionic conductance in the micro-nanofluidic interconnect system, with consideration of the electrical double layers (EDLs), is investigated. Regardless of the bulk salt concentration, significant enhancement of the flow rate is observed for viscoelastic fluid compared to the Newtonian fluid, due to the shear thinning effect. An increase in the ionic conductance of the nanochannel occurs for the viscoelastic fluid. The enhancement of the ionic conductance is significant under the overlapping EDLs condition.

scholarly journals Electroosmotic Flow of Viscoelastic Fluid through a Constriction Microchannel

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 417
Author(s):  
Jianyu Ji ◽  
Shizhi Qian ◽  
Zhaohui Liu
Keyword(s):  
Electric Field ◽  
Newtonian Fluid ◽  
Viscoelastic Fluid ◽  
Apparent Viscosity ◽  
Applied Electric Field ◽  
Electroosmotic Flow ◽  
Microfluidic Channel ◽  
Critical Value ◽  
Poisson Boltzmann ◽  
Boltzmann Model

Electroosmotic flow (EOF) has been widely used in various biochemical microfluidic applications, many of which use viscoelastic non-Newtonian fluid. This study numerically investigates the EOF of viscoelastic fluid through a 10:1 constriction microfluidic channel connecting two reservoirs on either side. The flow is modelled by the Oldroyd-B (OB) model coupled with the Poisson–Boltzmann model. EOF of polyacrylamide (PAA) solution is studied as a function of the PAA concentration and the applied electric field. In contrast to steady EOF of Newtonian fluid, the EOF of PAA solution becomes unstable when the applied electric field (PAA concentration) exceeds a critical value for a fixed PAA concentration (electric field), and vortices form at the upstream of the constriction. EOF velocity of viscoelastic fluid becomes spatially and temporally dependent, and the velocity at the exit of the constriction microchannel is much higher than that at its entrance, which is in qualitative agreement with experimental observation from the literature. Under the same apparent viscosity, the time-averaged velocity of the viscoelastic fluid is lower than that of the Newtonian fluid.

Slippage Effect on the Oscillatory Electroosmotic Flow of Power-Law Fluids in a Microchannel

2020 ◽  
Vol 399 ◽  
pp. 92-101
Author(s):  
Ruben Baños ◽  
José Arcos ◽  
Oscar Bautista ◽  
Federico Méndez
Keyword(s):  
Power Law ◽  
Electroosmotic Flow ◽  
Characteristic Length ◽  
Slip Length ◽  
Flow Behavior ◽  
Debye Length ◽  
Channel Width ◽  
Length Scale ◽  
Characteristic Length Scale ◽  
Power Law Fluids

The oscillatory electroosmotic flow (OEOF) under the influence of the Navier slip condition in power law fluids through a microchannel is studied numerically. A time-dependent external electric field (AC) is suddenly imposed at the ends of the microchannel which induces the fluid motion. The continuity and momentum equations in the and direction for the flow field were simplified in the limit of the lubrication approximation theory (LAT), and then solved using a numerical scheme. The solution of the electric potential is based on the Debye-Hückel approximation which suggest that the surface potential is small, say, smaller than 0:025V and for a symmetric () electrolyte. Our results suggest that the velocity profiles across the channel-width are controlled by the following dimensionless parameters: the dimensionless slip length , the Womersley number, , the electrokinetic parameter, , defined as the ratio of the characteristic length scale to the Debye length, the parameter which represents the ratio of the Helmholtz-Smoluchowski velocity to the characteristic length scale and the flow behavior index, . Also, the results reveal that the velocity magnitude gets higher values as increases and become more and more nonuniform across the channel-width as the and are increased, so OEOF can be useful in micro-fluidic devices such as micro-mixers.

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