Key words: Modeling, microchannel, fluid flow, heat transfer, ac electric field.

Abstract: In the last decade, microfluidics has flourished for their required in several sectors. The applications areas involved are huge, from the world of transport to the nuclear engineering, aerospace, engineering wind, and from biomechanics to the micro-electronics (e.g. cooling integrated circuits). In this paper, we present a numerical investigation of electrothermal fluid flow through a microchannel. The main purpose of this study is to investigate the flow instability induced by the electrothermal forces. The mathematical model includes the Navier-Stokes equation coupled with Maxwell and the balance energy equations. The equation system obtained is solved using the finite element method (FEM). The model provides insight and understanding of many physical and dynamic properties of flow. The numerical results show that the flow becomes highly unstable when the potential difference is great inducing the appearance of large swirls localized at the electrodes. Specifically, numerical calculations of voltage influence on the temperature and velocity of fluid flow fields are presented. Numerical suggest that 40 V applied to electrodes can increase maximum velocity by a factor of 600 compared to the inlet velocity. A slight increase in temperature (300 to 318 for Vrms = 40 V) was achieved.