Enhanced Electro-Osmotic Flow of Power-Law Fluids in Hydrophilic Patterned Nanochannel

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
M. Majhi ◽  
A. K. Nayak ◽  
A. Banerjee
Keyword(s):  
Power Law ◽  
Enhancement Factor ◽  
Random Phase ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Physical Parameters ◽  
Osmotic Flow ◽  
Power Law Fluids ◽  
Dilatant Fluid ◽  
Electro Osmotic Flow

Abstract In this paper, electro-osmotic flow (EOF) enhancement of non-Newtonian power-law fluids in a modulated nanochannel with polarized wall is proposed. The channel walls are embedded with periodically arranged rectangular grooves, placed vertically with the direction of electric field. The key aspect of the present study is to achieve enhanced EOF of power-law fluids due to periodic groove patterns. The flow characteristics are studied through Poisson–Nernst–Plank-based Navier–Stokes model associated with electrochemical boundary conditions. Some random-phase differences between the grooves in both the walls are allowed to find the best configuration for the EOF enhancement in case of both Pseudo-plastic fluid, Dilatant fluid, and compared to Newtonian fluid. A notable enhancement factor is observed when groove width is much larger than its depth along with overlapped EDL. It is also found that EOF enhancement for shear-thinning fluid is quite better than the other fluids, for the same set of physical parameters. A comparison of enhancement factor for power-law fluid is also presented when the grooves are replaced with hydrophobic strips. It is worth to mention here that the present study assumes no-slip condition which is true for wetting (hydrophilic) surface over nonwetting (hydrophobic) strips which is common occurrence in regards to nanoconfinements.

An Approximate Analytical Solution for Electro-Osmotic Flow of Power-Law Fluids in a Planar Microchannel

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Arman Sadeghi ◽  
Moslem Fattahi ◽  
Mohammad Hassan Saidi
Keyword(s):  
Nusselt Number ◽  
Power Law ◽  
Flow Behavior ◽  
Heat Fluxes ◽  
Flow Behavior Index ◽  
Osmotic Flow ◽  
Flow Parameters ◽  
Wall Heating ◽  
Power Law Fluids ◽  
Electro Osmotic Flow

The present investigation considers the fully developed electro-osmotic flow of power-law fluids in a planar microchannel subject to constant wall heat fluxes. Using an approximate velocity distribution, closed form expressions are obtained for the transverse distribution of temperature and Nusselt number. The approximate solution is found to be quite accurate, especially for the values of higher than ten for the dimensionless Debye-Huckel parameter where the exact values of Nusselt number are predicted. The results demonstrate that a higher value of the dimensionless Debye-Huckel parameter is accompanied by a higher Nusselt number for wall cooling, whereas the opposite is true for wall heating case. Although to increase the dimensionless Joule heating term is to decrease Nusselt number for both pseudoplastic and dilatant fluids, nevertheless its effect on Nusselt number is more pronounced for dilatants. Furthermore, to increase the flow behavior index is to decrease the Nusselt number for wall cooling, whereas the contrary is right for the wall heating case. Depending on the value of flow parameters, a singularity is observed in the Nusselt number values of the wall heating case.

scholarly journals 3D Model of Generalized Power Law Blood Flow in a Stenosed Bifurcated Artery

MATEMATIKA ◽  
2018 ◽  
Vol 34 (1) ◽  
pp. 87-102 ◽  
Author(s):  
Azim Azahari ◽  
Zuhaila Ismail ◽  
Normazni Abdullah
Keyword(s):  
Blood Flow ◽  
Power Law ◽  
Stokes Equations ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Parent Artery ◽  
Flow Recirculation ◽  
Power Law Fluids

Numerical simulation of the behaviour of blood flow through a stenosed bifurcated artery with the presence of single mild stenosis at parent artery is investigated. The flow analysis applies the incompressible, steady, three-dimensional Navier-Stokes equations for non-Newtonian generalized power law fluids. Behaviour of blood flow is simulated numerically using COMSOL Multiphysics that based on finite element method. The results show the effect of severity of stenosis on flow characteristics such as axial velocity and its exhibit flow recirculation zone for analysis on streamlines pattern.

scholarly journals On heat transfer of weakly compressible power-law flows

2017 ◽  
Vol 21 (6 Part B) ◽  
pp. 2709-2718
Author(s):  
Botong Li ◽  
Liangliang Zhu ◽  
Liancun Zheng ◽  
Wei Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Temperature Gradient ◽  
Power Law ◽  
Conductivity Model ◽  
Weakly Compressible ◽  
Power Law Fluids ◽  
Momentum And Heat Transfer ◽  
Thermal Conductivity Model ◽  
Dilatant Fluid

This paper completes a numerical research on steady momentum and heat transfer in power-law fluids in a channel. Weakly compressible laminar fluids are studied with no slip at the walls and uniform wall temperatures. The full governing equations are solved by continuous finite element method. Three thermal conductivity models are adopted in this paper, that is, constant thermal conductivity model, thermal conductivity varying as a function of temperature gradient, and a modified temperature-gradient-dependent thermal conductivity model. The results are compared with each other and the physical characteristics for values of parameters are also discussed in details. It is shown that the velocity curve from the solution becomes straight at higher power-law index. The effects of Reynolds numbers on the dilatant fluid and the pseudo-plastic look similar to each other and their trends can be easily predicted. Furthermore, for different models, the temperature curves also present pseudo-plastic and dilatant properties.

Electro-osmotic flow in microchannels

2008 ◽  
Vol 222 (5) ◽  
pp. 753-759 ◽  
Author(s):  
A K Arnold ◽  
P Nithiarasu ◽  
P F Eng
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Driven Systems ◽  
Osmotic Flow ◽  
Poisson Boltzmann ◽  
Wafer Surfaces ◽  
Flow Experiments ◽  
Complex Eof ◽  
Electro Osmotic Flow

In the current study, the modified Navier—Stokes equations together with the Poisson—Boltzmann and Laplace equations have been used to numerically model electro-osmotic flow (EOF) in straight microchannels. Flow experiments have been carried out using microchannels etched into silicon wafer surfaces. The numerical results from the present study have been compared against experimental data and an analytical solution. The results indicate that the numerical simulations are an accurate representation of EOF and that this model could be used as a tool in the design and analysis of complex EOF driven systems.

scholarly journals Numerical Analysis and Entropy Generation of Electrokinetic Flow of Power-Law Fluid in a Microtriangular Prism

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Fehaid Salem Alshammari
Keyword(s):  
Nusselt Number ◽  
Entropy Generation ◽  
Power Law ◽  
Second Law Of Thermodynamics ◽  
Physical Parameters ◽  
Electrokinetic Flow ◽  
Power Law Fluids ◽  
Transfer Equations ◽  
Constant Wall Heat Flux ◽  
Power Law Index

This research aims to study the characteristics of thermal transport and analyse the entropy generation of electroosmotic flow of power-law fluids in a microtriangular prism in the presence of pressure gradient. Considering a fully developed flow subject to constant wall heat flux, the nonlinear electric potential, momentum, and linear heat transfer equations are solved numerically by developing an iterative finite difference method with a nonuniform grid. The thermal efficiency of the model is explored under the light of the second law of thermodynamics. Effect/impact of governing physical parameters on velocity, temperature, Nusselt number, and entropy distributions is studied, and the results are demonstrated graphically; we found that the Nusselt number decreases with the increase of power-law index, and average entropy generation increases with power-law index. We believe that the obtained result in the present study shall be useful for design of energy efficient microsystems which utilize the dual electrokinetic and centrifugal pumping effects.

Study of Electroosmotic Flow in a Nanotube with Power Law Fluid

2011 ◽  
Vol 110-116 ◽  
pp. 3633-3638
Author(s):  
Davood D. Ganji ◽  
Mofid Gorji-Bandpy ◽  
Mehdi Mostofi
Keyword(s):  
Power Law ◽  
Navier Stokes ◽  
Equilibrium Equations ◽  
Flow Channels ◽  
Power Law Fluids ◽  
Fluid Properties ◽  
Poisson Boltzmann ◽  
The Subject ◽  
Poisson Boltzmann Equation ◽  
Electrochemical Equilibrium

In this paper, electroosmotic phenomena in power law fluids are investigated. This assumption is applicable in many cases such as blood. Flow channels assumed to be in nanoscale. Navier-Stokes, Poisson-Boltzmann and electrochemical equilibrium equations govern these phenomena. It is notable that, these governing equations should be modified according to fluid complexity. Electroosmotic phenomena occur in the presence of electric double layer (EDL). Potential in the edge of the inner layer (stern layer) is called zeta potential. In this paper, according to follow the applicability of the subject, zeta potential is assumed to be so small, that makes the Poisson-Boltzmann equation linear and be able to solve analytically. Method employed for analytical solution is based on developed Bessel differential equation. This paper aims to investigate the fluid properties, zeta potential and Debye-Huckel parameter effect on the viscosity, electroosmotic mobility and velocity field in the nanotube. These expected achievements help us to study the properties of blood and some other non-Newtonian fluids more precisely.

Numerical Simulations of Three-Dimensional Flows in a Cubic Cavity With an Oscillating Lid

1993 ◽  
Vol 115 (4) ◽  
pp. 680-686 ◽  
Author(s):  
Reima Iwatsu ◽  
Jae Min Hyun ◽  
Kunio Kuwahara
Keyword(s):  
Numerical Solutions ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Time Dependent ◽  
Navier Stokes ◽  
Physical Parameters ◽  
Navier Stokes Equations ◽  
Sinusoidal Oscillations ◽  
Dependent Flow

Numerical studies are made of three-dimensional flow of a viscous fluid in a cubical container. The flow is driven by the top sliding wall, which executes sinusoidal oscillations. Numerical solutions are acquired by solving the time-dependent, three-dimensional incompressible Navier-Stokes equations by employing very fine meshes. Results are presented for wide ranges of two principal physical parameters, i.e., the Reynolds number, Re ≤ 2000 and the frequency parameter of the lid oscillation, ω′ ≤ 10.0. Comprehensive details of the flow structure are analyzed. Attention is focused on the three-dimensionality of the flow field. Extensive numerical flow visualizations have been performed. These yield sequential plots of the main flows as well as the secondary flow patterns. It is found that the previous two-dimensional computational results are adequate in describing the main flow characteristics in the bulk of interior when ω′ is reasonably high. For the cases of high-Re flows, however, the three-dimensional motions exhibit additional complexities especially when ω′ is low. It is asserted that, thanks to the recent development of the supercomputers, calculation of three-dimensional, time-dependent flow problems appears to be feasible at least over limited ranges of Re.

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