Analysis of combined pressure-driven electroosmotic flow through square microchannels

Abstract

In this paper three-dimensional single-phase liquid flow through microchannels with a square-shaped cross-section driven by simultaneous application of pressure gradient and electroosmotic pumping mechanism is studied. The governing system of equations consists of the electric potential field and flow field equations. The solution procedure involves three steps. First, the net charge distribution on the cross-section of the microchannel is computed by solving two-dimensional Poisson-Boltzmann equation using the finite element method. Then, using the computed fluid's charge distribution, the magnitude of the resulting body force due to interaction of an external electric field with the charged fluid particles is calculated along the microchannel. In the third step, the flow equations are solved by considering three-dimensional Navier-Stokes equations with an electrokinetic body force. The computations reveal that the flow pattern in the microchannel is significantly different from the parabolic velocity profile of the laminar pressure-driven flow. The effect of the liquid bulk ionic concentration and the external electric field strength on flow patterns through the squareshaped microchannels is also investigated.

Numerical investigation of the electric double-layer effect on the performance of microchannel heat exchanger at combined electroosmotic and pressure-driven flow

“…It can be seen that from this Fig. 5 there is a good agreement between the mushtaq [8] present model results of the present model and that for [18] and the error between the model presented and a result of [18] less than 5 %.…”

“…To check the numerical model validity, verification was made by solving the model presented in [18] a compared the results. The model presented in [18] is a square microchannel at combined flow (electroosmosis flow and pressure-driven flow) with a hydraulic diameter of 25 μm, channel height 25 μm, channel width 25 μm, and length 100 μm with ∆P/dx = 10 5 pa/m , an inlet temperature of 289 K, and molar concentration 10 −4 M, 10 −5 M, zeta potential ζ = 150, 200 mV. Fig.…”

“…Fig. 5 shows the comparison between results of the data of [18] for velocity distribution with a width of microchannel at different ionic concentrations. It can be seen that from this Fig.…”

Unsteady electroosmosis in a microchannel with Poisson–Boltzmann charge distribution

“…Subsequently, their Chien C. Chang 1,2 Chih-Yu Kuo 1 Chang-Yi Wang method has been used by others [8][9][10]. Semi-empirical [11] and numerical solutions [12][13][14] have also been done. In the present study, a systematic perturbation in terms of l will be used to obtain accurate solutions for the PB equation which are uniformly valid for all K. Then the EOF due to an unsteady applied axial electric field is determined for a parallel-plate microchannel.…”

Lift Forces on Colloidal Particles in Combined Electroosmotic and Poiseuille Flow

“…Both numerical and experimental studies − have shown that driving a flow by imposing both a pressure gradient and an electric field will give a flow with a velocity field that is simply the superposition of the Poiseuille and EO flows for these creeping flows. Although Johann and Renaud used a combination of Poiseuille and EO flows, albeit in distinct regions of their microfluidic device, to sort yeast cells almost a decade ago, we know of no studies that have looked at how the forces due to the combination of a pressure gradient and an electric field affect the near-wall dynamics of rigid particles, much less cells, in such flows.…”