Electrokinetic energy conversion of core-annular flow in a slippery nanotube

Abstract

In this paper, the electrokinetic energy conversion of core-annular flow (CAF) is investigated theoretically in a slippery nanotube. Two immiscible and undisturbed fluids are full of the whole nanotube, consisting of a two-layer fluid system. The core fluid is assumed to be surrounded by the annular fluid with an ideal flow pattern. Based on the Debye–Hückel linearization, the analytical expressions of flow velocity, streaming potential and electrokinetic energy conversion efficiency have been obtained. Result shows that the CAF can be enhanced obviously by the permittivity and viscosity ratios. Compared with the classical single-layer fluid system, large streaming potential strength can be obtained by altering the annular fluid property in the present two-layer fluid system. This implies that more streaming current can be obtained. Besides, as a significant application of electrokinetic flow, the optimal ratios can also be obtained in the two-layer fluid system and the conversion efficiency attains the maximum at these optimal ratios.