Micromixers are crucial elements in microfluidic systems, indispensable for effective fluid mixing at the microscale. This study evaluates the dual Y-shaped straight channel (SC) micromixer, introducing three designs: sharp bend (SB), sharp bend with expansion–contraction (SB-EC), and sharp bend with expansion–contraction coupled with rhombus split recombination (SB-EC-RS). Their mixing performance is comprehensively assessed through both experimental and numerical simulations. Mixing index (MI), pressure drop, and mixing cost are quantitatively evaluated on the COMSOL 6.2a platform, across a Reynolds number range from 0.5 to 100. The results demonstrate that SB, SB-EC, and SB-EC-RS micromixers substantially improve mixing in comparison to SC, attributed to chaotic advection, Dean flow effects, and transverse flow synergy, which effectively renew mass transfer interfaces. The SB-EC-RS micromixer performs exceptionally well: at Re = 10, its mixing index reaches 0.9751, which is 3.029 times that of SB; at Re = 20, it further improves to 0.9991. Validation using red ink and de-ionized water indicates that when Re 1, the mixing index increases with Reynolds number, thereby enhancing chaotic advection and Dean flow, which generates local vortices and turbulence, thus improving mixing efficiency. This micromixer exhibits considerable advantages at low Reynolds numbers. The SB-EC-RS composite micromixer developed in this study offers an effective solution for optimizing mixing modules within microfluidic systems, facilitating the advancement of microfluidic devices toward enhanced efficiency, miniaturization, and cost-effectiveness.
Li et al. (Sun,) studied this question.