Mass Flow Rate Control in a Cylindrical Capillary by an AC Electric Field at High Zeta Potential

Abstract

In the present study we obtain the mass flow rate characteristics in a cylindrical capillary due to a time-periodic electric field at high zeta potential, extending the conventional thin electrical double layer limit. The capillary cross section is divided into two regimes, the high potential regime (near surface region), and the low potential regime (capillary central line region). To obtain the potential distribution inside the capillary, the nonlinear part of the Poisson-Boltzmann equation is approximated by a linear function for the low potential regime and by an exponential function for high potential regime. Using the approximated potential distributions, the governing electro-hydrodynamic equation is then solved semi-analytically, where the imposed electric field and the velocity field is assumed to have the form which consist of a steady state term and a time-periodic term. A theoretical investigation on the mass flow rate, the phase difference is carried out on the basis of pulsation frequency, e...