Numerical investigation of the effect of electrode arrangement and geometry on electrothermal fluid flow pumping and mixing in microchannel

Micro-mixers, due to their vast applications in different fields have been of great interest to the researchers in recent years. In this study, a transient two-dimensional solver was developed in the open-source code, OpenFOAM to simulate electrothermal effect in a micro mixer. Then, as the first step, the obtained mixing quality and fluid velocity of three different geometries with various electrode arrangements were compared. According to the results, the micromixer with a trapezoidal chamber and a circular cavity has the highest mixing and pumping efficiency. Then, in the selected micromixer, the effect of different parameters was studied such as voltage, electrode heating, electrical conductivity and size of electrode installed on the cavity and channel. The results showed that, in some phase differences, increasing the voltage improves the quality of mixing, and in others, it has an inverse effect. In addition, it is found that increasing size of electrodes in the cavity, decreases the fluid velocity and increases the mixing quality. Finally, by increasing voltage on different electrodes, a remarkable micro-mixer with a mixing quality of 99 % and an average fluid velocity of 64 mu m/s was obtained.