Numerical Simulation of Combined Electroosmotic and PressureDriven Flow in Cylindrical Microchannels at Large ZetaPotentials

In this paper mixed electro osmotic/pressure driven flow in cylindrical micro channels with large zeta potential on channel walls is discussed. The ion-distribution inside EDL, was described utilizing two different models including Debye-Huckle and Gouy-Chapman. Moreover assuming the channel characteristic length to be much greater than Debye length, the Poisson-Boltzmann equation was implemented. The governing equations, including Poisson-Boltzmann, continuity and modified Navier-Stokes Here solved numerically using a finite-volume code. The developed model, then implemented to investigate the accuracy and validity of different pictures of EDL at high zeta potentials. It was found that the Gouy-Chapmann picture of EDL verifies the best with available analytical solutions. Besides it was shown that, the magnitude of zeta potential can significantly alter the electro kinetic velocity shape and magnitude and this effect would be heightened by increasing the ratio of EDL thickness to channel characteristic length.