A study on the electroosmotic flow of micropolar fluid in a channel with hydrophobic walls

In the present study, the equations governing the electroosmotic flow in a horizontal microchannel with hydrophobic walls are solved using the micropolar fluid model analytically. The effects of the influential parameters, including micropolar viscosity, the ratio of characteristic length of the fluid microstructures to the characteristic length of the flow (m), concentration coefficient, Debye-Huckel parameter, the ratio of pressure-driven velocity to electroosmotic velocity (U-r), and slip coefficient, were examined on the flow pattern. According to the results, the magnitude of the velocity profile decreases as the micropolar viscosity, m, and U-r (U-r < 0) increase. The flow velocity grows as the concentration coefficient-dependent microgyration flow distribution increases, and the velocity distribution increases as the U-r (U-r > 0) and Debye-Huckel parameter acting as the flow's electric driving force. The slip coefficient has a direct impact on the velocity profile, considerably increasing its value. Thus, it can be concluded that small-scale surface slip is highly significant and helps achieve the best design of microchannel walls to control the flow in microchannels accurately. In addition, the contrast between decreasing velocity profile and increasing micropolar viscosity makes the micropolar fluid model an appropriate tool to simulate the fluid behavior in microstructures, given that it assumes gyration in the boundaries due to the existence of an electric field.