mixing enhancement of electroosmotic flow in microchannels under dc and ac electric field

A novel micromixer is presented in this study and the effect of dc or ac electric field on mixing efficiency is investigated numerically. four types of ac waveforms are considered to explore the flow characteristic and mixing efficiency. the velocity field, concentration field and the mixing efficiency are analyzed in details. the results demonstrated that a pair of vortices with opposite rotating directions is generated when dc or ac voltages is applied to the electrode plates planted within the walls. the generated vortices greatly enhance the mixing of incoming fluids with different concentrations. the mixing efficiency firstly rises with time and then reaches a relative stable periodic state under different potential waveforms. as the voltage applied on the plates increases, the mixing efficiency is improved obviously. the mixing efficiency under fullwave ac signal is the highest, and it is up to 95.44% when the applied potential is 3 v and frequency is 5 hz.