Electroviscous effect and electrokinetic energy conversion in time periodic pressure-driven flow through a parallel-plate nanochannel with surface charge-dependent slip

2018 ◽  
Vol 51 (20) ◽  
pp. 205601 ◽  
Author(s):  
Mandula Buren ◽  
Yongjun Jian ◽  
Yingchun Zhao ◽  
Long Chang
Keyword(s):  
Energy Conversion ◽  
Surface Charge ◽  
Parallel Plate ◽  
Electroviscous Effect ◽  
Periodic Pressure ◽  
Flow Through ◽  
Pressure Driven Flow ◽  
Time Periodic ◽  
Pressure Driven

scholarly journals Effects of surface charge and boundary slip on time-periodic pressure-driven flow and electrokinetic energy conversion in a nanotube

2019 ◽  
Vol 10 ◽  
pp. 1628-1635 ◽  
Author(s):  
Mandula Buren ◽  
Yongjun Jian ◽  
Yingchun Zhao ◽  
Long Chang ◽  
Quansheng Liu
Keyword(s):  
Energy Conversion ◽  
Surface Charge ◽  
Conversion Efficiency ◽  
Slip Length ◽  
Slip Flow ◽  
Energy Conversion Efficiency ◽  
Boundary Slip ◽  
Periodic Pressure ◽  
Time Periodic ◽  
Pressure Driven

Time-periodic pressure-driven slip flow and electrokinetic energy conversion efficiency in a nanotube are studied analytically. The slip length depends on the surface charge density. Electric potential, velocity and streaming electric field are obtained analytically under the Debye–Hückel approximation. The electrokinetic energy conversion efficiency is computed using these results. The effects of surface charge-dependent slip and electroviscous effect on velocity and electrokinetic energy conversion efficiency are discussed. The main results show that the velocity amplitude and the electrokinetic energy conversion efficiency of the surface charge-dependent slip flow are reduced compared with those of the surface charge-independent slip flow.

scholarly journals Electroviscous effect on fluid drag in a microchannel with large zeta potential

2015 ◽  
Vol 6 ◽  
pp. 2207-2216 ◽  
Author(s):  
Dalei Jing ◽  
Bharat Bhushan
Keyword(s):  
Zeta Potential ◽  
Surface Charge ◽  
Electrical Potential ◽  
Slip Condition ◽  
Double Layers ◽  
Electroviscous Effect ◽  
Fluid Drag ◽  
Pressure Driven Flow ◽  
Effect Of Surface ◽  
Pressure Driven

The electroviscous effect has been widely studied to investigate the effect of surface charge-induced electric double layers (EDL) on the pressure-driven flow in a micro/nano channel. EDL has been reported to reduce the velocity of fluid flow and increase the fluid drag. Nevertheless, the study on the combined effect of EDL with large zeta potential up to several hundred millivolts and surface charge depenedent-slip on the micro/nano flow is still needed. In this paper, the nonlinear Poisson–Boltzmann equation for electrical potential and ion distribution in non-overlapping EDL is first analytically solved. Then, the modified Navier–Stokes equation for the flow considering the effect of surface charge on the electrical conductivity of the electrolyte and slip length is analytically solved. This analysis is used to study the effect of non-overlapping EDL with large zeta potential on the pressure-driven flow in a microchannel with no-slip and charge-dependent slip conditions. The results show that the EDL leads to an increase in the fluid drag, but that slip can reduce the fluid drag. When the zeta potential is large enough, the electroviscous effect disappears for flow in the microchannel under a no-slip condition. However, the retardation of EDL on the flow and the enhancement of slip on the flow counteract each other under a slip condition. The underlying mechanisms of the effect of EDL with large zeta potential on fluid drag are the high net ionic concentration near the channel wall and the fast decay of electrical potential in the EDL when the zeta potential is large enough.

scholarly journals Rheology and microstructural evolution in pressure-driven flow of a magnetorheological fluid with strong particle–wall interactions

2012 ◽  
Vol 23 (9) ◽  
pp. 969-978 ◽  
Author(s):  
Murat Ocalan ◽  
Gareth H. McKinley
Keyword(s):  
Microfluidic Devices ◽  
Magnetorheological Fluid ◽  
Time Dependent ◽  
Mr Fluid ◽  
Flow Through ◽  
Fluid Particles ◽  
And Performance ◽  
Pressure Driven Flow ◽  
Actuator Design ◽  
Pressure Driven

The interaction between magnetorheological (MR) fluid particles and the walls of the device that retain the field-responsive fluid is critical as this interaction provides the means for coupling the physical device to the field-controllable properties of the fluid. This interaction is often enhanced in actuators by the use of ferromagnetic walls that generate an attractive force on the particles in the field-on state. In this article, the aggregation dynamics of MR fluid particles and the evolution of the microstructure in pressure-driven flow through ferromagnetic channels are studied using custom-fabricated microfluidic devices with ferromagnetic sidewalls. The aggregation of the particles and the time-dependent evolution in the microstructure is studied in rectilinear, expansion and contraction channel geometries. These observations help identify methods for improving MR actuator design and performance.

Numerical and Experimental Studies on Electrical Potential Distribution of Pressure Driven Flow in Parallel Plate Microchannels

2004 ◽  
Author(s):  
Fuzhi Lu ◽  
Jun Yang ◽  
Daniel Y. Kwok
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Parallel Plate ◽  
Potential Distribution ◽  
Continuity Equation ◽  
Electrical Potential ◽  
Double Layers ◽  
Linear Potential ◽  
Pressure Driven Flow ◽  
Pressure Driven

A number of papers have been published on the computational approaches to electrokinetic flows. Nearly all of these decoupled approaches rely on the assumption of the Poisson-Boltzmann equation and do not consider the effect of velocity field on the electric double layers. By means of a charge continuity equation, we present here a numerical model for the simulation of pressure driven flow with electrokinetic effects in parallel-plate microchannels. Our approach is similar to that given by van Theemsche et al. [Anal. Chem., 74, 4919 (2002)] except that we assumed liquid conductivity to be constant and allows simulation to be performed in experimental dimension. The numerical simulation requires the solution of the Poisson equation, charge continuity equation and the incompressible Navier-Stokes equations. The simulation is implemented in a finite-volume based Matlab code. To validate the model, we measured the electrical potential downstream along the channel surface. The simulated results were also compared with known analytical solutions and experimental data. Results indicate that the linear potential distribution assumption in the streaming direction is in general not valid, especially when the flow rate is large for the specific channel geometry. The good agreement between numerical simulation and experimental data suggests that the present model can be employed to predict pressure-driven flow in microchannels.

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