Numerical simulation of mixing at 1–1 and 1–2 microfluidic junctions

• Numerical simulation of mixing at microfluidic junctions.
• Validation using experimental and theoretical results.
• Comparison of conventional and new 1–1 and 1–2 microfluidic junctions.
• New designs of 1–1 and 1–2 microfluidic junctions to enhance mixing.
• Comparison of different approaches to enhance microfluidic mixing.

Computational fluid dynamics (CFD) simulations are carried out to evaluate mixing in different types of 1–1 and 1–2 microfluidic junctions. Computational approach adopted in the study is validated by comparing its predictions with theoretical and experimental results. Asymmetric microfluidic junctions are found to show better mixing than symmetric microfluidic junctions. Among asymmetric microfluidic junctions, mixing is found to improve with increasing skewness of the junction. A new 1–1 microfluidic junction named as OA 100–200 W-junction is found to give the best mixing among all 1–1 microfluidic junctions evaluated in this study. Based on this new 1–1 microfluidic junction, several 1–2 microfluidic junctions are conceptualized. Among these 1–2 microfluidic junctions a junction named as 100–200–1650 WY-junction is found to give the best mixing. Different approaches to improve microfluidic mixing viz simple-junction–complex-layout, complex-junction–simple-layout and complex-junction–complex-layout, are compared.