Numerical analysis of microscale electrohydrodynamic conduction pumping of liquid film

With the increasing demand for thermal management in electronic devices, microscale film transportation has become a research focus in recent years. This study numerically investigates the working mechanism of two-phase micro-electrohydrodynamic (EHD) conduction pumping. Simulations were performed with the open-source platform OpenFOAM based on the finite volume method. The volume of fluid method was utilized to track the air-liquid interface. A two-dimensional flush electrode configuration with a typical size of 240μm was considered. Results show that the flow system is controlled by three charge structures. The heterocharge layer generates the main driving force in the liquid bulk, and its transportation ability is limited by the film thickness. The interface charge layer can induce an additional electric force on the film's top surface, resulting in flow strength enhancement and interface deformation. The electric double layer (EDL) can enhance the asymmetry of the overall electric field and electric force distribution, thus improving or suppressing the pump flow rate depending on the zeta potential polarity. In addition, the effects of the interface charge and the EDL are weakened with an increase in film thickness. Insights provided by the present study will be helpful to researchers in designing an EHD-based two-phase heat transfer system.