Comparison of mixing performances of T, Y and arrow-shaped micromixers using Villermaux-Dushman protocol at low Reynolds number

Mixing performance is commonly assessed using the Villermaux–Dushman protocol. Mixing in passive mixers may need to be at very low Reynolds number (Re). This study is aimed at comparing the mixing performances of T, Y and arrow-shaped micromixers using the Villermaux–Dushman protocol at Re 26.5 was Y < T < arrow-shaped micromixers. At lower Re values, the order of performance based on the absorbance and the experimental mixing times, became inconsistent. However, the comparison of mixing performance based on predicted mixing time gave consistent order of performance at all Re values. The instability in UV absorbance of mixed reagents in Villermaux–Dushman protocol was noted as the major cause of the reported inconsistency at very low Re. The inadequacy of Villermaux–Dushman protocol at low Re was verified via facile solvent extraction test. A more reliable technique should be used to assess the mixing performance of micromixers at very low Re and on-line UV measurement should be adopted for the Villermaux–Dushman experiment.