Numerical study of microscale passive mixing in a 3-Dimensional spiral mixer design

Mixing of fluids becomes difficult if the length of the mixing channel is very small with size in microns. This is due to the lack of inertia and pre-eminence of viscous forces at low Reynolds numbers. The present study proposes a passive 3-dimensional spiral micromixer (SMM) and its Computational Fluid dynamics (CFD) study to scrutinize the mixing performance of water over a broad range of Reynolds numbers (2 ≤ Re ≤ 320). The obtained results were compared with a simple straight T-micromixer (STM) keeping the axial length same for both micromixers, which is 3000 µm. SMM appears to be much better and shows promising results with complete mixing (97.5%) of fluids species achieved at Re = 320 and minimum efficiency of 74.3 % achieved at Re = 66. Contrarily, STM shows comparatively poor results with a maximum mixing efficiency of 32 % for the highest Reynolds number (Re = 320). Thus, it is concluded that the proposed SMM design is an effective and significant choice for various micromixing applications. © 2022