Computational Fluid Dynamics Analysis of Novel Planar Split-and-Recombine Micromixers

In this paper, four planar split-and-recombine (SAR) micromixers with circular and square-shaped mixing units are proposed.Each mixer consists of four identical elements connected in series, arranged either in-line or orthogonally.The aspect ratio of the mixers was always maintained at 1, with both the height and width set to 0.2 mm.The primary focus was to examine the dependency of mixing preference on the mixer's geometry and Reynolds numbers.The numerical simulation was performed to evaluate mixing index, pressure drop, velocity vector, and flow dynamics for a Reynolds number range of 1-200.The proposed mixers offer much better performance than a straight T mixer with similar length and dimensions.The mixing index of Type-1 (Cir-1 & Sqr-1) mixer remains within a moderate range of 50%-60% for 40≤Re≤200.In contrast, Type-2 (Cir-2 & Sqr-2) micromixers showed good mixing throughout the tested range of Reynolds numbers.In particular, 80% mixing was achieved at Reynolds numbers greater than 80.The Cir-2 is the best-performing mixer, with 3.3 times higher efficiency and 2 times lower mixing energy cost than a straight T mixer.