Numerical analysis of mixed electroosmotic/pressure driven flow of power-law fluids in microchannels and micropumps

Mixed electroosmotic/pressure driven (EO/PD) flow of power-law fluids in microchannels and micropumps is analyzed using a numerical scheme based on the finite volume formulation. Effects of the fluid behavior index (n), zeta potential and electric double layer (EDL) thickness are investigated on characteristics of pure EO and mixed EO/PD flow of power-law fluids in microchannels and micropumps. Results show that the velocity profile becomes more plug-like as the fluid behavior index, decreases. Concerning EO micropumping of power-law fluids, it was found that higher volumetric flow rates can be expected in EO micropumping of pseudoplastic fluids (n < 1). It was observed that increase in zeta potential or decrease in EDL thickness results in higher pressure rise and volumetric flow rate of EO micropumping of pseudoplastic fluids, while these changes do not have considerable effects on pressure rise and the volumetric flow rate of EO micropumping of dilatant fluids (n > 1). Moreover, pressure rise of power-law fluid in a closed system (zero net flow rate) under the influence of EO forces was studied and it was revealed that a higher pressure rise can be generated as the fluid behavior index decreases. (C) 2010 Elsevier B.V. All rights reserved.