Enhanced mixing characteristics in a spiral micromixer with grooves having variable configurations: A computational analysis

Abstract

The efficient and rapid mixing of fluids in a microfluidic channel is a challenging issue as it requires a large channel length and time to obtain the desired mixing. The mixing and hydrodynamic performance of spiral micromixers with grooves of different sizes, shapes, and numbers are examined in this work throughout a Reynolds number (Re) range of 1–150. Three distinct groove widths (100 µm, 125 µm, and 150 µm) were investigated for circular groove (CG) and rectangular groove (RG) shapes, and the total number of grooves was adjusted between four and fifteen. The results are compared to those from a spiral micromixer without grooves (spiral-noG). The results show that the mixing index increases with the number of grooves and groove width, with CG-15G having the maximum mixing efficiency across all Re. Wider grooves (150 µm) perform better than narrower ones, whereas groove shape has minimal impact on mixing. The CG-150 and RG-150 configurations provide notable increases in mixing at low Re (=1–10), with improvements ranging from +2.89% to +48.89%. At intermediate Re (=30–60), notable improvements are also seen, for example, at Re = 30, RG-150 shows an improvement of +87.54%. RG-150 consistently exhibits the highest pressure drop, though, as the number of grooves increases. Spiral-noG has the lowest cost at both low and high Re, but mixing costs increase in all configurations. The study concludes that micromixers with CG-100 and CG-125 are the best for mixing efficiency alone, while spiral-noG and CG-4G are suggested for real-world applications for a balance between mixing and pressure drop.