Coupled-Physics Modeling of Electrostatic Fluid Accelerators for Forced Convection Cooling

Classic thermal management solutions are becoming inadequate and there is an increasing need for fundamentally new approaches. Electrohydrodynamic ionic wind pumps, also known as electrostatic fluid accelerators (EFA), have the potential for becoming a critical element in electronics thermal management solutions. As the EFA field continues to evolve, developing new EFA-based technologies will require accurate models that can help predict pump performance metrics, such as air velocity profile, back pressure, and cooling efficiency. Many previous modeling efforts only account for electrostatic interactions. For truly accurate modeling, however, it is important to include effects of fluid dynamics and space charge diffusion. The modeling problem becomes especially challenging for the design and optimization of EFA devices with greater complexity and smaller dimensions. This paper presents a coupled-physics finite element model (FEM) that accounts for space charge generation from a corona discharge, as well as space charge diffusion and fluid dynamic effects in EFAs. A cantilever EFA structure is modeled and analyzed for forced convection cooling. Numerical modeling predicts maximum air velocities of approximately 7 m/s and a maximum convection heat transfer coefficient of 282 W/(m 2 K) for the cantilever EFA structure investigated. Preliminary experimental results for a microfabriacted cantilever EFA device for forced convection cooling are also discussed.