CFD analysis of electrostatic fluid accelerators for forced convection cooling

Abstract

Classic thermal management solutions for microelectronics 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 effectiveness. 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 in charge transport. 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) using a complete EFA charge transport model including charge diffusion and fluid dynamic effects. A cantilever EFA structure is modeled and analyzed for forced convection cooling. Numerical modeling predicts maximum air velocities of approximately 4 m/s and a maximum convection heat transfer coefficient of 280 W/(m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> K) for the cantilever EFA structure investigated. Preliminary experimental results for a microfabricated cantilever EFA device for forced convection cooling are also discussed.