Rotating Electroosmotic Flow Of Power-Law Fluids At High Zeta Potentials In Microchannel

Recently, microfluidic devices have been greatly applied in microbiological sensors and micro-electromechanic system. Advanced microfluidic devices can perform complete biochemical analysis in a single fabricated chip. Since the exchange of charges in channel wall and electrolyte, the free ions are either attracted to or repelled from a charged surface depending on the sign of the surface charges. Such a redistribution of free ions together with the surface ions gives rise to electric double layer (EDL). Electroosmotic flow (EOF) is the flow induced by the application of electric field across the channel and due to the presence of EDL at the channel wall. In the field of microfluidics, the EOF attracts much research attention of the scholars due to many operational advantages, such as a plug-like velocity, negligible axial dispersion and better flow control.In this paper, rotating electroosmotic flow (EOF) of power-law fluids at high zeta potentials in a slit microchannel is analyzed. The electric double layer (EDL) potential distribution is considered by using nonlinear Poisson-Boltzmann equation. Based upon the analytical charge density distribution, the finite difference method is used to compute numerically rotating EOF velocity profiles of power-law fluids. Results of the present analysis are compared with a simplified analysis obtained by Debye-Huckel linear approximation when the fluid is Newtonian. The classical steady plug-shape EOF velocity of Non-Newtonian fluid is reduced for large enough time if the rotating effect is ignored. Additionally, the influences of the flow behavior index n, the rotating angular velocity Ω, wall Zeta potential ψw and the electrodynamic width K on the velocity profiles are discussed in detail.