Combined effects of EDL and boundary slip on mean flow and its stability in microchannels

Abstract

The effects of an electrical double layer (EDL), boundary slip and their combined effects on the microchannel flow stability are investigated. Instead of applying the traditional streaming electrical current balance (ECB) mode, a newly introduced electrical current density balance (ECDB) mode is used to compute the conduction current when the effects of EDL is considered. The modified N-S equations and Poisson–Boltzmann equation together with the ECDB mode and Navier slip boundary are the theoretical basis for the present approach. The stability analysis considering the modifications of EDL and boundary slip is built up by the small perturbation method. It is found that the effect of EDL results in inflexions on the mean velocity profile near walls and destabilizes the stability of flow. On the contrary, the effect of boundary slip stabilizes the stability of flow. The effectiveness of boundary slip on the mean velocity and flow stability is influenced strongly by the effect of EDL. The effect of boundary slip can be disappeared when the Zeta potential is large enough.