关键词: 电渗流, 雷诺数, 双电层, 自由面

Abstract: A thin film flow on a cylinder driven by electro-osmosis in direct current (DC) and alternating current (AC) electric field are analytically investigated respectively. Analytical solutions of electric potential and flow velocity are obtained by solving viscous incompressible hydrodynamic equations coupling with linearized
Possion-Boltzmann equation based on the leaky dielectric model and the Debye-H¨uckel approximation. In a DC electric field, the dimensionless flow velocity just differs from the electric potential by a constant. The flow velocity on free surface only depends on a ratio α between the electric potential on the free surface and the potential on the cylindrical surface. In an AC electric field, the results show the amplitude of flow velocity. The phase difference between flow velocity in flow field and that in the electrical double layer is closely related to the Reynolds number. Amplitude of flow velocity in an AC periodic electric field is similar to that in a DC steady electric field in low Reynolds number. With the increase of the Reynolds number, the amplitude of flow velocity decreases near the solid surface, while the phase difference increases. The amplitude of flow velocity on a free surface decreases/increases as the Reynolds number increases for low/high α.