Mixing Performance of a Passive Micromixer Based on Multiple Baffles and Submergence Scheme

Area of Science:

• Microfluidics
• Fluid Dynamics
• Chemical Engineering

Background:

• Efficient mixing is crucial in microfluidic devices for various applications.
• Passive micromixers offer a low-complexity solution for enhancing mixing.
• The design of baffles and submergence features can significantly impact mixing performance.

Purpose of the Study:

• To design and simulate a novel passive micromixer utilizing multiple baffles and a submergence scheme.
• To evaluate the mixing performance and pressure drop across a wide range of Reynolds numbers (0.1 to 80).
• To investigate the effect of different submergence schemes on the degree of mixing (DOM).

Main Methods:

• Computational fluid dynamics (CFD) simulations were employed to analyze the micromixer's performance.
• The degree of mixing (DOM) at the outlet and pressure drop were key performance metrics.
• Simulations covered Reynolds numbers from 0.1 to 80, with specific focus on low (Re < 5) and high (Re > 10) flow regimes.

Main Results:

• The novel micromixer demonstrated significant mixing enhancement across the studied Reynolds number range.
• At low Reynolds numbers (Re < 5), the Sub24 submergence scheme yielded the highest DOM (~0.57), a 1.38x increase.
• At high Reynolds numbers (Re > 10), the Sub1234 scheme achieved the highest DOM (~0.93 at Re=20), a 2.75x increase, due to large vortex formation.

Conclusions:

• The proposed passive micromixer with baffles and submergence effectively enhances mixing efficiency.
• Specific submergence schemes are optimal for different flow regimes, with Sub24 for low Re and Sub1234 for high Re.
• Optimized submergence depths were determined for various schemes and Reynolds numbers, independent of the number of mixing units.