Pulsatile flow micromixing coupled with ICEO for non-Newtonian fluids

Abstract

The most biofluids/polymers, which are extensively used in lab-on-a-Chip devices exhibit non-Newtonian characteristics, whose mixing behaviors become crucial for the most engineering applications. For this purpose, the present numerical study investigates the performance of pulsatile flow micromixer coupled with induced-charge electro-osmosis (ICEO) for non-Newtonian fluids, such as power-law and Carreau. The mixing characteristics of Newtonian fluids are also presented and compared to non-Newtonian cases. The straight microchannel geometry is modified using rectangular obstruction with various heights to increase stirring performance for non-Newtonian fluids. The magnitude of the external electric field, the frequency of pulsatile flow and the width of rectangular obstruction are systematically varied for a comprehensive parametric evaluation. Time-dependent patterns of streamline and corresponding concentration maps are illustrated for qualitative presentation. Moreover, mixing index values are plotted versus obstruction width, the frequency of pulsatile flow and imposed electric field strength for quantitative analysis. It is observed that pulsatile flow with ICEO yields reasonable performance for all type of fluids. However, a rectangular obstruction is required to obtain maximum performance of mixing of non-Newtonian fluids for the given time, t = 10 s and length, l = 0.7 mm. It can be reported that rectangular obstruction has a significant effect on mixing performance for current conditions.