The Effect of High Zeta Potentials on the Flow Hydrodynamics in Parallel-Plate Micro-Channels

This paper investigates the effect of the EDL at the solid-liquid interface on theliquid flow through a micro-channel formed by two parallel plates. The completePoisson-Boltzmann equation (without the frequently used linear approximation)was solved analytically in order to determine the EDL field near the solid-liquidinterface. The momentum equation was solved analytically taking intoconsideration the electrical body force resulting from the EDL field. Effects of thechannel size and the strength of the zeta-potential on the electrostatic potential,the streaming potential, the velocity profile, the volume flow rate, the apparentviscosity, and the friction factor are presented and discussed. Results of thepresent analysis, which are based on the complete Poisson-Boltzmann equation,are compared with a simplified analysis that used a linear approximation of thePoisson-Boltzmann equation.