Numerical Investigation of Flow Patterns and Mixing Characteristics in a 3D Micromixer with Helical Elements over Wide Reynolds Numbers

Micromixers play an important role in the micro total analysis systems (µTAS) that require rapid and effective mixing. However, current micromixers are usually designed to meet the need for mixing at limited Reynolds numbers. Herein, this paper presents a high-performance 3D micromixer with helical elements over wide Reynolds numbers to achieve efficient mixing and has numerically investigated flow patterns and mixing characteristics accordingly. A coupled numerical model is built to analyze the flow pattern, mixing behavior, residence time distribution (RTD), and mixing performance of the 3D micromixer. Helical elements inside could greatly enhance a secondary flow and induce chaotic advection around. Dean vortices are observed in the micromixer, enormously shortening the RTD and promoting the related mixing effect. Furthermore, the effects of various geometric parameters are systematically investigated to optimize the performance of this 3D micromixer. The optimized micromixer shows excellent mixing ability over wide Reynolds numbers ranging from 0.01 to 2333.3, with an efficiency of over 94%. In addition, the numerical results are proved well consistent with analytical and experimental data correspondingly. Therefore, this work would potentially expand the use scope of 3D micromixers and provide a constructive strategy to develop essential parts involving the mixing or reacting process in µTAS.