Electrohydrodynamic conduction pumping of viscoelastic dielectric liquids on the microscale

Electrohydrodynamic (EHD) conduction pumping can be applied in many macroscopic devices accompanied by a high electric field intensity (10⁶ V/m). Microscale flow generation has become increasingly important with the widespread development of thermal management devices, which are currently used to cool high heat flux sources with small surface areas and are found in a variety of electronic, controlled heat transfer, and aerospace scenarios. Additionally, the magnitude of the applied voltage can be significantly reduced in micropumping, resulting in power savings and a reliable method for flow generation. In this study, we examine the dynamic characteristics of a conduction micropump embedded within a rectangular microchannel, showing the effects of Coulombic driving forces, different channel heights, polymer elasticity, and viscosity ratios. The results show that electric power consumption can vary by two orders of magnitude for increasing channel height. As the polymer concentration increases, the maximum velocity decreases significantly and can reach 50% of that of the unadded polymer with a plunger-like distribution. The flow rate depends linearly on the polymer concentration, but exhibits non-monotonic curve with the polymer elasticity. It means that the flow rate performance of the micro-pump can be kept controllable by tuning the viscosity ratio, providing some suggestions for some regulated flow applications.