Nonlinear Smoluchowski velocity for electroosmosis of Power-law fluids over a surface with arbitrary zeta potentials

2010 ◽  
Vol 31 (5) ◽  
pp. 973-979 ◽  
Author(s):  
Cunlu Zhao ◽  
Chun Yang
Keyword(s):  
Power Law ◽  
Zeta Potentials ◽  
Power Law Fluids

scholarly journals An Exact Solution for Power-Law Fluids in a Slit Microchannel with Different Zeta Potentials under Electroosmotic Forces

Micromachines ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 504 ◽  
Author(s):  
Du-Soon Choi ◽  
Sungchan Yun ◽  
WooSeok Choi
Keyword(s):  
Power Law ◽  
Applied Pressure ◽  
Debye Length ◽  
Momentum Equation ◽  
Microfluidic System ◽  
Zeta Potentials ◽  
Power Law Fluids ◽  
Poisson Boltzmann ◽  
The Difference ◽  
Poisson Boltzmann Equation

Electroosmotic flow (EOF) is one of the most important techniques in a microfluidic system. Many microfluidic devices are made from a combination of different materials, and thus asymmetric electrochemical boundary conditions should be applied for the reasonable analysis of the EOF. In this study, the EOF of power-law fluids in a slit microchannel with different zeta potentials at the top and bottom walls are studied analytically. The flow is assumed to be steady, fully developed, and unidirectional with no applied pressure. The continuity equation, the Cauchy momentum equation, and the linearized Poisson-Boltzmann equation are solved for the velocity field. The exact solutions of the velocity distribution are obtained in terms of the Appell’s first hypergeometric functions. The velocity distributions are investigated and discussed as a function of the fluid behavior index, Debye length, and the difference in the zeta potential between the top and bottom.

scholarly journals Electroviscous Effect of Power Law Fluids in a Slit Microchannel With Asymmetric Wall Zeta Potentials

2018 ◽  
Vol 35 (4) ◽  
pp. 537-547 ◽  
Author(s):  
A. Sailaja ◽  
B. Srinivas ◽  
I. Sreedhar
Keyword(s):  
Zeta Potential ◽  
Power Law ◽  
Streaming Potential ◽  
Shear Thickening ◽  
Narrow Slit ◽  
Electroviscous Effect ◽  
Streaming Potentials ◽  
Zeta Potentials ◽  
Power Law Fluids ◽  
Poisson Boltzmann Equation

ABSTRACTThis work analyzes the pressure driven flow of a power law fluid in a slit microchannel of asymmetric walls with electroviscous effects. The steady state Cauchy momentum and the Poisson-Boltzmann equation are solved for the velocity and the potential distribution inside the microchannel. The Debye-Huckel approximation as applicable for low zeta potentials is not made in the present work. The unknown streaming potential is solved by casting the governing equations as an optimization problem using COMSOL Multiphysics. This proposed method is very robust and can be used for a wide variety of cases. It is found that the asymmetry of the zeta potential at the two walls plays an important role on the streaming potential developed. There is a unique zeta potential ratio at which the streaming potential exhibits a maxima for both Debye-Huckel parameter and the power law index. Shear thinning fluids exhibit a stronger dependency of the streaming potential on asymmetry of the zeta potential than shear thickening fluids. For Newtonian fluids narrow slit microchannels develop larger streaming potentials compared to wider microchannels for a given asymmetry.

Forced convection heat transfer study of a blunt-headed cylinder in non-Newtonian power-law fluids

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jaspinder Kaur ◽  
Roderick Melnik ◽  
Anurag Kumar Tiwari
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Drag Coefficient ◽  
Power Law ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Total Drag ◽  
Shear Thinning Fluids ◽  
Power Law Fluids

Abstract In this present work, forced convection heat transfer from a heated blunt-headed cylinder in power-law fluids has been investigated numerically over the range of parameters, namely, Reynolds number (Re): 1–40, Prandtl number (Pr): 10–100 and power-law index (n): 0.3–1.8. The results are expressed in terms of local parameters, like streamline, isotherm, pressure coefficient, and local Nusselt number and global parameters, like wake length, drag coefficient, and average Nusselt number. The length of the recirculation zone on the rear side of the cylinder increases with the increasing value of Re and n. The effect of the total drag coefficient acting on the cylinder is seen to be higher at the low value of Re and its effect significant in shear-thinning fluids (n < 1). On the heat transfer aspect, the rate of heat transfer in fluids is increased by increasing the value of Re and Pr. The effect of heat transfer is enhanced in shear-thinning fluids up to ∼ 40% and it impedes it’s to ∼20% shear-thickening fluids. In the end, the numerical results of the total drag coefficient and average Nusselt number (in terms of J H −factor) have been correlated by simple expression to estimate the intermediate value for the new application.

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