Numerical study on the mixing quality of an electroosmotic micromixer under periodic potential

Improvement of the mixing quality of low Reynolds number flows in micro-dimensional devices is essential. This paper investigates the optimization of the effective parameters and their effects on the mixing quality in a two-dimensional active micromixer. The micromixer mixes fluids with different concentrations entering into a microchannel from different inlets by means of four microelectrodes placed on the walls of a mixing chamber. A time-dependent electric field is applied, and the resulting electroosmotic force perturbs the parallel streamlines in the otherwise highly ordered laminar flow. The governing equations are numerically solved using the finite element-based COMSOL Multiphysics (Version 5.2a) software. The electroosmotic actuated active micromixer was numerically studied for various values of inlet velocity, phase lag, frequency, and voltage amplitude. Once the optimum values of the effective parameters are obtained for the original micromixer, they are applied to the micromixers having different obstacle shape inside the mixing chamber. The results showed that the mixing quality strongly depends on the inlet velocity of the fluids, the electrodes phase lag, the frequency, and the voltage amplitude. In addition, the mixing quality does not depend on obstacle shape when the optimum values of these parameters were used.