Numerical investigation of the effect of the electrodes bed on the electrothermally induced fluid flow velocity inside a microchannel

Abstract

Due to the development of technology, desire of using fluid pumping systems without movable components in micro scale is increased, which Electrokinetics is one of them. One of the sub-sets of this method is the electrothermal phenomenon. This phenomenon, being the focus of researchers because of its ability in pumping fluids with high electrical conductivity (more than 0.01S/m). There are different software for simulating this phenomenon, such as fluent and COMSOL Metaphysics, which could say cover most of them. In this paper, initially introduce new solver based of OpenFOAM for this phenomenon. Next, various geometry for the electrodes bed and their related parameters are investigated. At this part, initially the effect of different configuration of the electrodes bed on the fluid velocity inside a microchannel is investigated. Because the objective of this part is comparing different beds geometries for the electrode, only two pairs of electrodes are used. Results show that the bed with upward trapezoid, isosceles and acute configuration for electrodes bed have the best performance, which increase outlet velocity of the fluid 34.4% and 33% compared to flat mode, respectively. Secondly, the effect of the gap between the electrode pairs, the placement of acute trapezoidal configuration is investigated. By applying the best state of the examined parameters, fluid velocity in the trapezoidal channel with two and six pairs of electrodes increases up to 79.45% and 118% respectively. In the third section, a correlation between the fluid velocity at the outlet and ratio of various channel heights in respect to the trapezoid's height is derived. This Equation indicates direct relation between the outlet velocity and the channel height.