Keywords: 
• 电致流动 /
• 液体薄膜 /
• 方波电场 /
• 液膜的转动

Abstract: Liquid film motor as a novel experimental device will play an important role in basic research and technology applications. Indepth theoretical studies on its electro-hydrodynamics （EHD） motions under various conditions are of great significance. In current paper, the dynamical characteristics of the liquid film motor driven by a square-wave electrophoresis electric field perpendicular to a uniform constant external electric field are investigated. Space-time dependence of the film＇s rotation linear velocity is derived analytically. The theoretical results indicate that a symmetrical reciprocating rotation in the film gradually converts to a vibration as the frequency of the electrophoresis electric field increases. This not only helps us understand the physical origin of the vibration of the liquid film motor, but also provides a new option to design a liquid film mixer in the application.